From aniketsuniljoshi at gmail.com Mon Jan 4 07:37:01 2016
From: aniketsuniljoshi at gmail.com (Aniket Joshi)
Date: Mon, 4 Jan 2016 13:07:01 +0530
Subject: [GAP Forum] Using M12 semidirect product Z_2 in GAP
Message-ID:
Hi,
I wish to find the homology H_3(M_{12} : Z_2, Z), where M_{12} is a Mathieu
group of order 95040, and M_12:Z_2 indicates the semi-direct product with
Z_2. I plan to use the GroupHomology(,) command from the HAP package for
GAP.
How do I use the semi direct product M_12:Z_2 in GAP? Is there an inbuilt
function, or would I need to compute it separately?
Regards,
Aniket
--
Aniket S Joshi
4th year B.S.-M.S. Physics Dual Degree
Roll no. PH11B001
Department of Physics, IIT Madras
From dmitrii.pasechnik at cs.ox.ac.uk Mon Jan 4 15:18:45 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dmitrii Pasechnik)
Date: Mon, 4 Jan 2016 15:18:45 +0000
Subject: [GAP Forum] Using M12 semidirect product Z_2 in GAP
In-Reply-To:
References:
Message-ID: <20160104151845.GA28704@cs.ox.ac.uk>
On Mon, Jan 04, 2016 at 01:07:01PM +0530, Aniket Joshi wrote:
> I wish to find the homology H_3(M_{12} : Z_2, Z), where M_{12} is a Mathieu
> group of order 95040, and M_12:Z_2 indicates the semi-direct product with
> Z_2. I plan to use the GroupHomology(,) command from the HAP package for
> GAP.
>
> How do I use the semi direct product M_12:Z_2 in GAP? Is there an inbuilt
> function, or would I need to compute it separately?
just take
assuming you have AltasRep package installed, you can just do
AtlasGroup("M12:2")
to get a permutation representation of M:12:2 on 24 points.
HTH,
Dmitrii
From graham.ellis at nuigalway.ie Mon Jan 4 15:24:29 2016
From: graham.ellis at nuigalway.ie (Ellis, Grahamj)
Date: Mon, 4 Jan 2016 15:24:29 +0000
Subject: [GAP Forum] Using M12 semidirect product Z_2 in GAP
In-Reply-To: <20160104151845.GA28704@cs.ox.ac.uk>
References: ,
<20160104151845.GA28704@cs.ox.ac.uk>
Message-ID:
And here is the computation showing that H_3(M12:2, Z) = Z_2 x z_2 x Z_12.
gap> LoadPackage("atlasrep");;
gap> G:=AtlasGroup("M12:2");;
gap> GroupHomology(G,3);
[ 2, 2, 4, 3 ]
Graham
School of Mathematics, Statistics & Applied Mathematics
National University of Ireland, Galway
University Road,
Galway
Ireland
http://hamilton.nuigalway.ie
tel: 091 493011
________________________________________
From: forum-bounces at gap-system.org [forum-bounces at gap-system.org] on behalf of Dmitrii Pasechnik [dmitrii.pasechnik at cs.ox.ac.uk]
Sent: Monday, January 4, 2016 3:18 PM
To: Aniket Joshi
Cc: forum at gap-system.org
Subject: Re: [GAP Forum] Using M12 semidirect product Z_2 in GAP
On Mon, Jan 04, 2016 at 01:07:01PM +0530, Aniket Joshi wrote:
> I wish to find the homology H_3(M_{12} : Z_2, Z), where M_{12} is a Mathieu
> group of order 95040, and M_12:Z_2 indicates the semi-direct product with
> Z_2. I plan to use the GroupHomology(,) command from the HAP package for
> GAP.
>
> How do I use the semi direct product M_12:Z_2 in GAP? Is there an inbuilt
> function, or would I need to compute it separately?
just take
assuming you have AltasRep package installed, you can just do
AtlasGroup("M12:2")
to get a permutation representation of M:12:2 on 24 points.
HTH,
Dmitrii
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
From sara.yaftian at gmail.com Tue Jan 5 10:50:00 2016
From: sara.yaftian at gmail.com (Sara Yaftian)
Date: Tue, 5 Jan 2016 14:20:00 +0330
Subject: [GAP Forum] A question about ParGAP
Message-ID:
Dear Forum
I have a question about ParGAP.
I installed parGAP by the following command
cd pargap
./configure
make
and then I need mpi and I installed mpi.
Finally I paralleled a GAP program on Linux (Ubuntu 14.04 LTS) by the
following command:
mpiexe -np 5 ./pargap.sh
when GAP run then I typed Read("myprogram.txt");
I am not sure my commands are correct or not because my laptop use 5 of CPU
but the speed of my program has not changed. Would you please help me?
I wish you have a very happy New Year 2016.
Best regards
Sara
From axyd0000 at gmail.com Tue Jan 5 13:05:38 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Tue, 5 Jan 2016 18:35:38 +0530
Subject: [GAP Forum] Meaning of `\=` operation in GAP
Message-ID:
Hi, GAP members
I want to know the exact purpose for which `\=` i.e equality operation is
used in GAP. Does `\=` checks for the mathematical equality or does it
check for structural equality (of given objects) or some other type of
equality of objects in GAP that i am not aware of?
It will be very helpful if you provide the examples indicating the behavior
(mathematical or structural), particularly either with `FreeGroup` or
`Permutation Groups`.
Thanks
Gaurav Dhingra
From caj21 at st-andrews.ac.uk Tue Jan 5 13:20:50 2016
From: caj21 at st-andrews.ac.uk (Christopher Jefferson)
Date: Tue, 5 Jan 2016 13:20:50 +0000
Subject: [GAP Forum] Meaning of `\=` operation in GAP
In-Reply-To:
References:
Message-ID: <695FAFF4-E57F-4B3D-AEF4-BC4B43000AEA@st-andrews.ac.uk>
The equality operation should always compare for mathematical equality. I agree the documentation could be slightly improved in this area.
For example, the following two permutation groups are equal, as they are both the complete permutation group on 4 points.
gap> Group([(1,2),(2,3,4)]) = Group([(1,4),(2,3,4)]);
true
On 05/01/2016, 13:05, "forum-bounces at gap-system.org on behalf of Gaurav Dhingra" wrote:
>Hi, GAP members
>
>I want to know the exact purpose for which `\=` i.e equality operation is
>used in GAP. Does `\=` checks for the mathematical equality or does it
>check for structural equality (of given objects) or some other type of
>equality of objects in GAP that i am not aware of?
>It will be very helpful if you provide the examples indicating the behavior
>(mathematical or structural), particularly either with `FreeGroup` or
>`Permutation Groups`.
>
>Thanks
>Gaurav Dhingra
>_______________________________________________
>Forum mailing list
>Forum at mail.gap-system.org
>http://mail.gap-system.org/mailman/listinfo/forum
From oyvind.solberg at math.ntnu.no Tue Jan 5 15:39:43 2016
From: oyvind.solberg at math.ntnu.no (=?UTF-8?Q?=c3=98yvind_Solberg?=)
Date: Tue, 5 Jan 2016 16:39:43 +0100
Subject: [GAP Forum] question concerning the GAP package qpa (how to get an
inclusion mprphism?)
In-Reply-To:
References:
Message-ID: <568BE3BF.1030902@math.ntnu.no>
Dear GAP Forum and Bernhard,
Suppose we are given a finite dimensional quotient A = kQ/I of a path
algebra and two modules M and N over A, where we know that N is
a submodule of M. If M and N are given as two representations/
modules over A and you have not told QPA how N is a submodule of
M, then there is in general no way QPA can find the inclusion you are
thinking about. In general a module N can be a submodule of a given
module M in infinitely many ways. However, if you know by which
elements N is generated by inside M, say m_1, m_2,..., m_t, then the
command
gap> g := SubRepresentationInclusion(M, [m1,m2,...,mt]);
will produce an inclusion from a module N' isomorphic to N into M, but
where the images inside M are the same. Then to get an inclusion from
N you could find an isomorphism between N and N' by
gap> alpha := IsomorphismOfModules( N, N' );
and then find the composition alpha*g.
If you are just abstractly knowing that N is a submodule of M, then I
don't
know an algorithm to find an inclusion of N into M.
Best regards, Oeyvind Solberg.
From angelblascomunoz at gmail.com Tue Jan 5 20:36:46 2016
From: angelblascomunoz at gmail.com (Angel Blasco)
Date: Tue, 5 Jan 2016 21:36:46 +0100
Subject: [GAP Forum] =?utf-8?q?Save_=E2=80=9Ctime=E2=80=9D_in_a_variable_i?=
=?utf-8?q?n_GAP?=
Message-ID:
Hi,
I'm trying to write a program in GAP to obtain the time that GAP needs to
construct the groups of an order given. I'm using the command:
ConstructAllGroups(order);;time;
Is there anyway to save the value of "time" in a variable?
I did it with:
a:=ConstructAllGroups(10);;time;
but only the groups were saved.
Regards
--
*Angel Blasco.*
From hulpke at math.colostate.edu Tue Jan 5 20:43:21 2016
From: hulpke at math.colostate.edu (Alexander Hulpke)
Date: Tue, 5 Jan 2016 13:43:21 -0700
Subject: [GAP Forum]
=?utf-8?q?Save_=E2=80=9Ctime=E2=80=9D_in_a_variable_i?=
=?utf-8?q?n_GAP?=
In-Reply-To:
References:
Message-ID: <218F3214-39A9-44CB-93FB-B2A3158D8CFB@math.colostate.edu>
> I'm trying to write a program in GAP to obtain the time that GAP needs to
> construct the groups of an order given. I'm using the command:
>
> ConstructAllGroups(order);;time;
>
> Is there anyway to save the value of "time" in a variable?
Yes, time is just like a variable (this is different to the time command in unix and other systems):
a:=ConstructAllGroups(10);;savedtime:=time;
Within a program I would rather refer to the value of Runtime(), that is:
start:=Runtime();
a:=ConstructAllPiffles(-33);
total:=Runtime()-start;
Best,
Alexander Hulpke
-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke
From sl4 at st-andrews.ac.uk Tue Jan 5 20:41:56 2016
From: sl4 at st-andrews.ac.uk (Stephen Linton)
Date: Tue, 5 Jan 2016 20:41:56 +0000
Subject: [GAP Forum]
=?windows-1252?q?Save_=93time=94_in_a_variable_in_GAP?=
In-Reply-To:
References:
Message-ID: <232E9C66-442E-4F95-99A1-3242509FA4A0@st-andrews.ac.uk>
ConstructAllGroups(order);; a := time;
ought to work, but you might want to look into the Runtime() function to get an
interface designed more for programming.
Steve
> On 5 Jan 2016, at 20:36, Angel Blasco wrote:
>
> Hi,
>
> I'm trying to write a program in GAP to obtain the time that GAP needs to
> construct the groups of an order given. I'm using the command:
>
> ConstructAllGroups(order);;time;
>
> Is there anyway to save the value of "time" in a variable?
> I did it with:
>
> a:=ConstructAllGroups(10);;time;
>
> but only the groups were saved.
>
>
> Regards
> --
> *Angel Blasco.*
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From angelblascomunoz at gmail.com Tue Jan 5 20:52:06 2016
From: angelblascomunoz at gmail.com (Angel Blasco)
Date: Tue, 5 Jan 2016 21:52:06 +0100
Subject: [GAP Forum]
=?utf-8?q?Save_=E2=80=9Ctime=E2=80=9D_in_a_variable_i?=
=?utf-8?q?n_GAP?=
In-Reply-To: <218F3214-39A9-44CB-93FB-B2A3158D8CFB@math.colostate.edu>
References:
<218F3214-39A9-44CB-93FB-B2A3158D8CFB@math.colostate.edu>
Message-ID:
thanks
2016-01-05 21:43 GMT+01:00 Alexander Hulpke :
> > I'm trying to write a program in GAP to obtain the time that GAP needs to
> > construct the groups of an order given. I'm using the command:
> >
> > ConstructAllGroups(order);;time;
> >
> > Is there anyway to save the value of "time" in a variable?
>
> Yes, time is just like a variable (this is different to the time command
> in unix and other systems):
>
> a:=ConstructAllGroups(10);;savedtime:=time;
>
> Within a program I would rather refer to the value of Runtime(), that is:
>
> start:=Runtime();
> a:=ConstructAllPiffles(-33);
> total:=Runtime()-start;
>
> Best,
>
> Alexander Hulpke
>
> -- Colorado State University, Department of Mathematics,
> Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
> email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
> http://www.math.colostate.edu/~hulpke
>
>
>
--
*Angel Blasco.*
From alexk at mcs.st-and.ac.uk Tue Jan 5 21:30:14 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Tue, 5 Jan 2016 21:30:14 +0000
Subject: [GAP Forum] A question about ParGAP
In-Reply-To:
References:
Message-ID: <7CEC0812-336F-4A43-9F3D-8016F5F627A9@mcs.st-andrews.ac.uk>
Dear Sara,
> On 5 Jan 2016, at 10:50, Sara Yaftian wrote:
>
> Dear Forum
>
> I have a question about ParGAP.
> I installed parGAP by the following command
>
> cd pargap
> ./configure
> make
>
> and then I need mpi and I installed mpi.
> Finally I paralleled a GAP program on Linux (Ubuntu 14.04 LTS) by the
> following command:
>
> mpiexe -np 5 ./pargap.sh
Thank you for your question, and Happy New Year to you too! The above
steps seem to be correct. The rest depends on what "myprogram.txt" is
doing - it is quite common that when one tries to parallelise the code
then the first version of the parallel code runs slower than the
sequential one.
Also, the phrase "I paralleled a GAP program" sounds a bit ambiguous, so
just in case: what
mpiexe -np 5 ./pargap.sh
command is doing is that it starts several copies of GAP. One of them is
called 'master', and it provides the GAP command line interface and
communicates with all the others, called 'slaves'. If you will call
Read("myprogram.txt");
but the code there does not use any master-slave communication, it will
just perform the calculation on the master.
Best wishes
Alexander
>
> when GAP run then I typed Read("myprogram.txt");
>
> I am not sure my commands are correct or not because my laptop use 5 of CPU
> but the speed of my program has not changed. Would you please help me?
>
> I wish you have a very happy New Year 2016.
>
> Best regards
> Sara
From axyd0000 at gmail.com Wed Jan 6 05:29:40 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Wed, 6 Jan 2016 10:59:40 +0530
Subject: [GAP Forum] Find the source for in GAP
Message-ID:
Hi GAP members
I asked previously
http://math.stackexchange.com/questions/1570893/which-algorithm-gap-uses-to-check-equality-of-two-groups
for finding the source of an "operation" in GAP. Also there is already an
answer for finding the source of a "function" in GAP.
My question is how to find the source of an "Attribute" in GAP?
For ex. i want to find the Algorithm for finding the `stabilizer` of a
`SymmetricGroup`
gap> s4:=SymmetricGroup(4);
Sym( [ 1 .. 4 ] )
gap> Stabilizer;
function( arg ) ... end
gap> StabilizerOfExternalSet; # this is used for SymmetricGroup in
particular
gap> func:=ApplicableMethod(StabilizerOfExternalSet, [s4]);
fail
gap>
It fails. Is there another method instead of using `ApplicableMethod`?
Above i used `StabilizerOfExternalSet` after seeing the source code for
`Stabilizer`.
Gaurav Dhingra
From sl4 at st-andrews.ac.uk Wed Jan 6 09:45:00 2016
From: sl4 at st-andrews.ac.uk (Stephen Linton)
Date: Wed, 6 Jan 2016 09:45:00 +0000
Subject: [GAP Forum] Find the source for in GAP
In-Reply-To:
References:
Message-ID:
Dear Gaurav,
Attributes are just like Operations, and you can use ApplicableMethod in the same way. A good example is Size:
gap> g := Group((1,2,3,4,5),(1,5)(2,4));
Group([ (1,2,3,4,5), (1,5)(2,4) ])
gap> ApplicableMethod(Size,[g]);
function( G ) ... end
gap> Print(last);
function ( G )
return SizeStabChain( StabChainMutable( G ) );
end
However, there is one complication, which is that once an Attribute has been computed the value is often stored in which case the
method changes to one that just recovers the stored value:
gap> Size(g);
10
gap> ApplicableMethod(Size,[g]);
function( object ) ... end
gap> Print(last);
function ( object )
<>
end
gap>
Stabilizer, however is not itself an attribute and is rather more complicated. See:
http://www.gap-system.org/Manuals/doc/ref/chap41.html#X797BD60E7ACEF1B1
and also section 41.12 a bit further down.
It doesn?t make sense to ask simply about the Stabilizer of a group ? you also have to specify an object to be
stabilised and an action of the group and the call goes through a number of functions that fill in missing arguments and detect special cases before eventually reaching a call of StabilizerOp or StabilizerOfExternalSet where the work is really done.
Steve
> On 6 Jan 2016, at 05:29, Gaurav Dhingra wrote:
>
> Hi GAP members
>
> I asked previously
> http://math.stackexchange.com/questions/1570893/which-algorithm-gap-uses-to-check-equality-of-two-groups
> for finding the source of an "operation" in GAP. Also there is already an
> answer for finding the source of a "function" in GAP.
>
> My question is how to find the source of an "Attribute" in GAP?
> For ex. i want to find the Algorithm for finding the `stabilizer` of a
> `SymmetricGroup`
>
> gap> s4:=SymmetricGroup(4);
> Sym( [ 1 .. 4 ] )
> gap> Stabilizer;
> function( arg ) ... end
> gap> StabilizerOfExternalSet; # this is used for SymmetricGroup in
> particular
>
> gap> func:=ApplicableMethod(StabilizerOfExternalSet, [s4]);
> fail
> gap>
>
> It fails. Is there another method instead of using `ApplicableMethod`?
> Above i used `StabilizerOfExternalSet` after seeing the source code for
> `Stabilizer`.
>
> Gaurav Dhingra
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From sashar.sashar1360 at gmail.com Mon Jan 11 08:02:50 2016
From: sashar.sashar1360 at gmail.com (sashar sashar)
Date: Mon, 11 Jan 2016 00:02:50 -0800
Subject: [GAP Forum] Does Irr(g) return the principle character as its first
entry?
Message-ID:
Dear Forum,
I am working with SmallGroups Library.I have used the function
Irr(SmallGroup(n,i)) for some ns and is. I have noticed that the pincipal
character 1_G is the first entry for these groups. Is this always true for
all the groups in SmallGroups Library?
Regards
Sashar
From angelblascomunoz at gmail.com Wed Jan 13 19:25:26 2016
From: angelblascomunoz at gmail.com (Angel Blasco)
Date: Wed, 13 Jan 2016 20:25:26 +0100
Subject: [GAP Forum] How can I fix this problem using Cubefree package
Message-ID:
I'm trying to calculate the number of groups of order 815409. I'm using
Cubefree package but after 2 minutes processing my pc returns me this:
gap> NumberCFGroups(815409);
Error, Record: '.orbit' must have an assigned value in
pnt := S.orbit[1]; called from
StabChainStrong( S, GeneratorsOfGroup( G ), options ); called from
StabChainOp( G, rec(
base := [ 1 .. LargestMovedPoint( G ) ] ) ) called from
MinimalStabChain( G ) called from
GeneratorsSmallest( b ) called from
Set( C1 ) called from
... at line 2 of *stdin*
you can 'return;' after assigning a value
brk>
How can I fix this problem?
Regards
--
*Angel Blasco.*
From heiko.dietrich at monash.edu Wed Jan 13 19:51:15 2016
From: heiko.dietrich at monash.edu (Heiko Dietrich)
Date: Thu, 14 Jan 2016 08:51:15 +1300
Subject: [GAP Forum] How can I fix this problem using Cubefree package
Message-ID:
Dear Angel,
This is a known bug which is fixed in the latest version; please download
version 1.15 from here and extract it in your /pkg directory of your gap
installation:
http://users.monash.edu/~heikod/cubefree.html
(This version should actually be listed on the gap website
http://www.gap-system.org/Packages/cubefree.html but it isn't -- Alex?!?)
Anyway, the result of this computation is
gap> n:=NumberCFGroups(815409);
415
Best,
Heiko
-----------------------------------------
On Thu, 14/1/16, Angel Blasco wrote:
I'm trying to calculate the number of groups of order 815409. I'm using
Cubefree package but after 2 minutes processing my pc returns me this:
gap> NumberCFGroups(815409);
Error, Record: '.orbit' must have an assigned value in
pnt := S.orbit[1]; called from
StabChainStrong( S, GeneratorsOfGroup( G ), options ); called from
StabChainOp( G, rec(
base := [ 1 .. LargestMovedPoint( G ) ] ) ) called from
MinimalStabChain( G ) called from
GeneratorsSmallest( b ) called from
Set( C1 ) called from
... at line 2 of *stdin*
you can 'return;' after assigning a value
brk>
How can I fix this problem?
Regards
--
*Angel Blasco.*
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
--
*Dr HEIKO DIETRICH *
*School of Mathematical Sciences*
Monash University
Clayton Campus
9 Rainforest Walk
Monash University VIC 3800
Australia
T: +61 3 9905 4771
E: heiko.dietrich at monash.edu
users.monash.edu/~heikod
From angelblascomunoz at gmail.com Wed Jan 13 19:56:46 2016
From: angelblascomunoz at gmail.com (Angel Blasco)
Date: Wed, 13 Jan 2016 19:56:46 +0000 (UTC)
Subject: [GAP Forum] How can I fix this problem using Cubefree package
In-Reply-To:
References:
Message-ID: <6A8E708086FF1F89.F6880071-CB63-4F3B-8B93-60E183B9BB84@mail.outlook.com>
Ok, i've got GAP 4.7.9 installed and the cubefree package inside is 1.13 Now i'm going to download and install version 1.15 in my pkg folder.
Thanks
Enviado desde Outlook Mobile
On Wed, Jan 13, 2016 at 11:51 AM -0800, "Heiko Dietrich" wrote:
Dear Angel,
This is a known bug which is fixed in the latest version; please download version 1.15 from here and extract it in your /pkg directory of your gap installation:
?? http://users.monash.edu/~heikod/cubefree.html
(This version should actually be listed on the gap website http://www.gap-system.org/Packages/cubefree.html but it isn't -- Alex?!?)
Anyway, the result of this computation is
gap> n:=NumberCFGroups(815409);
415
Best,
Heiko
-----------------------------------------
On Thu, 14/1/16, Angel Blasco wrote:
I'm trying to calculate the number of groups of order 815409. I'm using
Cubefree package but after 2 minutes processing my pc returns me this:
gap> NumberCFGroups(815409);
Error, Record: '.orbit' must have an assigned value in
? pnt := S.orbit[1]; called from
StabChainStrong( S, GeneratorsOfGroup( G ), options ); called from
StabChainOp( G, rec(
? ? base := [ 1 .. LargestMovedPoint( G ) ] ) ) called from
MinimalStabChain( G ) called from
GeneratorsSmallest( b ) called from
Set( C1 ) called from
...? at line 2 of *stdin*
you can 'return;' after assigning a value
brk>
How can I fix this problem?
Regards
--
*Angel Blasco.*
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
--
Dr HEIKO DIETRICH ?? ? ? ? ? ? ? ?
School of Mathematical Sciences
Monash UniversityClayton Campus9 Rainforest Walk
Monash University VIC 3800Australia
T: +61 3 9905 4771? ? ? ? ? ? ? ? ? ? ??E: heiko.dietrich at monash.eduusers.monash.edu/~heikod
From alexk at mcs.st-and.ac.uk Wed Jan 13 23:04:57 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Wed, 13 Jan 2016 23:04:57 +0000
Subject: [GAP Forum] How can I fix this problem using Cubefree package
In-Reply-To:
References:
Message-ID:
Dear all,
> On 13 Jan 2016, at 19:51, Heiko Dietrich wrote:
>
> Dear Angel,
>
> This is a known bug which is fixed in the latest version; please download version 1.15 from here and extract it in your /pkg directory of your gap installation:
>
> http://users.monash.edu/~heikod/cubefree.html
Yes - see also my former comments under http://math.stackexchange.com/q/1607419/
>
> (This version should actually be listed on the gap website http://www.gap-system.org/Packages/cubefree.html but it isn't -- Alex?!?)
The packages pages on the GAP website are not dynamic - they are updated only after the GAP public release, and reflect the set of packages included in that release. Thus at the moment they match GAP 4.7.9.
When I am telling package authors that the new version has been picked up, it's only the initial step. It is followed by a nightly and weekly testing cycle. It could happen that the package is incompatible with the system or other packages, and then will be put on hold.
You may see the current status report on package updates at this Wiki page:
https://github.com/gap-system/gap/wiki/Package-updates-status
and also see how packages progress between testing stage:
https://trello.com/b/CTsB9FTl/package-updates-name-version-pickup-date
At the moment, Cubefree 1.15 passes tests of the release candidate for the public release of GAP 4.8, so it should be safe to use it.
Best wishes
Alexander
> Anyway, the result of this computation is
>
> gap> n:=NumberCFGroups(815409);
> 415
>
> Best,
> Heiko
>
>
>
>
> -----------------------------------------
> On Thu, 14/1/16, Angel Blasco wrote:
> I'm trying to calculate the number of groups of order 815409. I'm using
> Cubefree package but after 2 minutes processing my pc returns me this:
>
> gap> NumberCFGroups(815409);
> Error, Record: '.orbit' must have an assigned value in
> pnt := S.orbit[1]; called from
> StabChainStrong( S, GeneratorsOfGroup( G ), options ); called from
> StabChainOp( G, rec(
> base := [ 1 .. LargestMovedPoint( G ) ] ) ) called from
> MinimalStabChain( G ) called from
> GeneratorsSmallest( b ) called from
> Set( C1 ) called from
> ... at line 2 of *stdin*
> you can 'return;' after assigning a value
> brk>
>
>
> How can I fix this problem?
>
> Regards
>
> --
> *Angel Blasco.*
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
> --
> Dr HEIKO DIETRICH
>
> School of Mathematical Sciences
> Monash University
> Clayton Campus
> 9 Rainforest Walk
> Monash University VIC 3800
> Australia
>
> T: +61 3 9905 4771
> E: heiko.dietrich at monash.edu
> users.monash.edu/~heikod
--
Dr. Alexander Konovalov FSSI, Senior Research Fellow
Centre for Interdisciplinary Research in Computational Algebra (CIRCA)
School of Computer Science, University of St Andrews
http://blogs.cs.st-andrews.ac.uk/alexk/
--
The University of St Andrews is a charity registered in Scotland:No.SC013532
From sara.yaftian at gmail.com Thu Jan 14 13:44:16 2016
From: sara.yaftian at gmail.com (Sara Yaftian)
Date: Thu, 14 Jan 2016 17:14:16 +0330
Subject: [GAP Forum] A question about ParGAP
In-Reply-To: <7CEC0812-336F-4A43-9F3D-8016F5F627A9@mcs.st-andrews.ac.uk>
References:
<7CEC0812-336F-4A43-9F3D-8016F5F627A9@mcs.st-andrews.ac.uk>
Message-ID:
Dear Alexander
Thank you very much for your helpful message. I have a question about your
last message.
How to use master-salve communication?
On the other hand, I need to use 5 CPU's, but MPI in ParGAP used 2 CPU's.
Is there any command to solve this problem?
Best regards
Sara
On Wed, Jan 6, 2016 at 1:00 AM, Alexander Konovalov
wrote:
> Dear Sara,
>
> > On 5 Jan 2016, at 10:50, Sara Yaftian wrote:
> >
> > Dear Forum
> >
> > I have a question about ParGAP.
> > I installed parGAP by the following command
> >
> > cd pargap
> > ./configure
> > make
> >
> > and then I need mpi and I installed mpi.
> > Finally I paralleled a GAP program on Linux (Ubuntu 14.04 LTS) by the
> > following command:
> >
> > mpiexe -np 5 ./pargap.sh
>
> Thank you for your question, and Happy New Year to you too! The above
> steps seem to be correct. The rest depends on what "myprogram.txt" is
> doing - it is quite common that when one tries to parallelise the code
> then the first version of the parallel code runs slower than the
> sequential one.
>
> Also, the phrase "I paralleled a GAP program" sounds a bit ambiguous, so
> just in case: what
>
> mpiexe -np 5 ./pargap.sh
>
> command is doing is that it starts several copies of GAP. One of them is
> called 'master', and it provides the GAP command line interface and
> communicates with all the others, called 'slaves'. If you will call
>
> Read("myprogram.txt");
>
> but the code there does not use any master-slave communication, it will
> just perform the calculation on the master.
>
> Best wishes
> Alexander
>
>
>
>
>
>
>
>
> >
> > when GAP run then I typed Read("myprogram.txt");
> >
> > I am not sure my commands are correct or not because my laptop use 5 of
> CPU
> > but the speed of my program has not changed. Would you please help me?
> >
> > I wish you have a very happy New Year 2016.
> >
> > Best regards
> > Sara
>
>
>
From tim at algebra.uni-linz.ac.at Fri Jan 15 15:12:47 2016
From: tim at algebra.uni-linz.ac.at (Tim Boykett)
Date: Fri, 15 Jan 2016 17:12:47 +0200
Subject: [GAP Forum] Shortest words
Message-ID: <56990C6F.7020504@algebra.uni-linz.ac.at>
Dear GAPpers,
I have previously used the techniques outlined in the Rubik's Cube
tutorial to find words expressing certain permutations in the generators
I am using. This has worked fine so far, but I have run up against a
problem where I would like to prefer some permutations and use as few as
possible of others. It seems that the very old collection AbStab.g used
to do this, but it is no longer part of GAP. What is the current way to
do this?
I am sure there is a very simple technique, but I cannot seem to find it.
Best wishes,
Tim
From e.obrien at auckland.ac.nz Sun Jan 17 08:40:03 2016
From: e.obrien at auckland.ac.nz (Eamonn O'Brien)
Date: Sun, 17 Jan 2016 21:40:03 +1300
Subject: [GAP Forum] Two jobs available at the University of Auckland
Message-ID: <569B5363.7090109@auckland.ac.nz>
Dear Colleagues:
The Department of Mathematics at the University of Auckland invites
applications for two permanent full-time positions at Lecturer / Senior
Lecturer level. We expect that at least one of these will be filled at
Lecturer level.
We expect that the research expertise of the successful applicants will
complement existing research strengths in Pure Mathematics. These
include: graph theory and combinatorics; group theory; number theory;
and representation theory. More details about the Department can be
found at www.math.auckland.ac.nz
The job advertisement, including details of the application process, is
available at:
https://www.math.auckland.ac.nz/en/about/news-and-events/notices/notices-2015/2015/12/job-opportunities--lecturership----senior-lecturership.html
Closing date: 14 February, 2016
I am happy to provide additional information, and appreciate if you can
draw the attention of your colleagues to these positions.
Best wishes.
Eamonn O'Brien
From fima.math at gmail.com Tue Jan 19 09:50:39 2016
From: fima.math at gmail.com (Fima Bahari)
Date: Tue, 19 Jan 2016 13:20:39 +0330
Subject: [GAP Forum] Hamiltoniancycle
Message-ID:
Dear all,
By GAP, Is it possible to fine a Hamiltonian cycle in a defined graph, if
it exists?
Many thanks in advance
From sam at Math.RWTH-Aachen.De Wed Jan 20 09:07:50 2016
From: sam at Math.RWTH-Aachen.De (Thomas Breuer)
Date: Wed, 20 Jan 2016 10:07:50 +0100
Subject: [GAP Forum] Does Irr(g) return the principle character as its
first entry?
In-Reply-To:
References:
Message-ID: <20160120090747.GA1440@gemma.math.rwth-aachen.de>
Dear Sashar,
you asked the GAP Forum
> I am working with SmallGroups Library.I have used the function
> Irr(SmallGroup(n,i)) for some ns and is. I have noticed that the pincipal
> character 1_G is the first entry for these groups. Is this always true for
> all the groups in SmallGroups Library?
No.
The method that is chosen by GAP for computing
the irreducible characters of a group
depends on properties of this group
and not on the library from which it is constructed.
For example,
there is a method for computing the irreducible characters
of a symmetric group in its natural representation;
this method uses the fact that the conjugacy classes of the group
are parametrized by the cycle structures of the group elements.
This method is applicable only if the group has this property
and if this property is stored in the group
before the call to the function `Irr',
and currently this method can be expected to be used in this situation.
Here is a sample GAP session.
gap> g:= SmallGroup( 120, 34 ); # the symmetric group on five points
Group([ (1,2,3,4,5), (1,2) ])
gap> Position( Irr( g ), TrivialCharacter( g ) );
1
gap> g:= SmallGroup( 120, 34 ); # fetch the group again
Group([ (1,2,3,4,5), (1,2) ])
gap> IsNaturalSymmetricGroup( g ); # now the group stores the property
true
gap> Position( Irr( g ), TrivialCharacter( g ) );
7
Note that the GAP manual states explicitly that the trivial character
need not be the first entry in the list of irreducible characters.
All the best,
Thomas
From angelblascomunoz at gmail.com Fri Jan 29 19:34:36 2016
From: angelblascomunoz at gmail.com (Angel Blasco)
Date: Fri, 29 Jan 2016 20:34:36 +0100
Subject: [GAP Forum] Hamiltonian groups
Message-ID: <56ABBECC.6050605@gmail.com>
Is there any command in GAP to generate a Hamiltonian group of an order
given?
Thanks
From fima.math at gmail.com Sat Jan 30 07:05:33 2016
From: fima.math at gmail.com (Fima Bahari)
Date: Sat, 30 Jan 2016 10:35:33 +0330
Subject: [GAP Forum] Fwd: Hamiltoniancycle
In-Reply-To:
References:
Message-ID:
---------- Forwarded message ----------
From: Fima Bahari
Date: Tue, Jan 19, 2016 at 1:20 PM
Subject: Hamiltoniancycle
To: forum at mail.gap-system.org
Dear all,
By GAP, Is it possible to fine a Hamiltonian cycle in a defined graph, if
it exists?
Many thanks in advance
From l.h.soicher at qmul.ac.uk Sat Jan 30 09:24:20 2016
From: l.h.soicher at qmul.ac.uk (Leonard Soicher)
Date: Sat, 30 Jan 2016 09:24:20 +0000
Subject: [GAP Forum] Fwd: Hamiltoniancycle
In-Reply-To:
References: ,
,
Message-ID:
Dear Fima, Dear Forum,
There is no GRAPE function to find a Hamiltonian cycle (when such a cycle exists)
in a given graph. However, the free open-source SageMath system has a function for this.
See http://doc.sagemath.org/pdf/en/reference/graphs/graphs.pdf
Regards,
Leonard
________________________________________
From: forum-bounces at gap-system.org on behalf of Fima Bahari
Sent: 30 January 2016 07:05
To: forum at gap-system.org
Subject: [GAP Forum] Fwd: Hamiltoniancycle
---------- Forwarded message ----------
From: Fima Bahari
Date: Tue, Jan 19, 2016 at 1:20 PM
Subject: Hamiltoniancycle
To: forum at mail.gap-system.org
Dear all,
By GAP, Is it possible to fine a Hamiltonian cycle in a defined graph, if
it exists?
Many thanks in advance
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
From axyd0000 at gmail.com Thu Feb 4 18:30:50 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Fri, 5 Feb 2016 00:00:50 +0530
Subject: [GAP Forum] Inequality of Generators of Finitely Presented and
corresponding Free Group
Message-ID: <56B398DA.8060601@gmail.com>
Hi, GAP forum members
I am reading this particular documentation
http://www.gap-system.org/Manuals/doc/ref/chap47.html , from this page i
quote this sentence
> That means that words in the generators of the free group are not
elements of the finitely presented group. Vice versa elements of the
FpGroup are not words.
There is also an example showing this behavior. Now, i don't why this
has been done. I mean is there is any particular reason for why GAP
authors did it this way? (for defining equality between the generators).
Feel free explain in detail even if it is completely some development
methodology (or non-mathematical) which has been followed for this.
Thanks
Gaurav Dhingra
From kroberts at math.uni-bielefeld.de Fri Feb 5 08:54:41 2016
From: kroberts at math.uni-bielefeld.de (Kieran Roberts)
Date: Fri, 5 Feb 2016 09:54:41 +0100
Subject: [GAP Forum] Default Arguments
Message-ID:
Dear GAP forum:
Is it possible to include default arguments in a function?
Such as something like this (which doesn't work):
add := function(a,b:=1)
return a+b;
end;
So that add(2,2) = 4 and add(2) = 3. The only way I've managed to do
is by writing:
add := function(arg)
if Size(arg) = 2 then
return arg[1] + arg[2];
else
return arg[1] + 1;
fi;
end;
But if you have 2 or 3 (optional) arguments with default values this
becomes cumbersome. Is there a more efficient way?
Best,
Kieran.
From alexander.konovalov at st-andrews.ac.uk Tue Feb 9 21:57:58 2016
From: alexander.konovalov at st-andrews.ac.uk (Alexander Konovalov)
Date: Tue, 9 Feb 2016 21:57:58 +0000
Subject: [GAP Forum] Default Arguments
In-Reply-To:
References:
Message-ID: <34FDD10F-A182-4C5A-B539-1915868FBB83@st-andrews.ac.uk>
Dear Kieran,
> On 5 Feb 2016, at 08:54, Kieran Roberts wrote:
>
> Dear GAP forum:
>
> Is it possible to include default arguments in a function?
>
> Such as something like this (which doesn't work):
>
> add := function(a,b:=1)
> return a+b;
> end;
>
> So that add(2,2) = 4 and add(2) = 3. The only way I've managed to do
> is by writing:
>
> add := function(arg)
> if Size(arg) = 2 then
> return arg[1] + arg[2];
> else
> return arg[1] + 1;
> fi;
> end;
>
> But if you have 2 or 3 (optional) arguments with default values this
> becomes cumbersome. Is there a more efficient way?
This will a bit easier in coming soon GAP 4.8: as written at
https://github.com/gap-system/gap/wiki/Changes-between-GAP-4.7-and-GAP-4.8
it will have "support for partially variadic functions to allow function
expressions like
function(a,b,c,x...) ... end;
which would require at least three arguments and assign the first three to
a, b and c and then a list containing any remaining ones to x. The former
special meaning of the argument arg is still supported and is now equivalent
to function(arg...), so no changes in the existing code are required."
The example from above could then look like
gap> add := function(a,b...)
> if Length(b)=0 then
> return a+1;
> else
> return a+b[1];
> fi;
> end;
function( a, b... ) ... end
gap> add(2,2);
4
gap> add(2);
3
If you have more optional arguments, they would all go into the list b,
but since you would be no longer obliged to use the special name 'arg',
your code may be more readable because of using proper identifiers for
mandatory arguments.
Best wishes
Alexander
From rahul.kitture at gmail.com Wed Feb 10 04:34:44 2016
From: rahul.kitture at gmail.com (Rahul Kitture)
Date: Wed, 10 Feb 2016 10:04:44 +0530
Subject: [GAP Forum] A question on factorization of an integer
Message-ID:
Dear Sir,
In some computations of orders of groups, which turn out to be large, I
wanted to see the prime factorization of the order. For example, I use
following kind of commands:
gap> g:=SymmetricGroup(10);; Size(g);
3628800
gap> Factors(3628800);
[ 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 5, 5, 7 ]
My question is, is there some command in GAP to get this factorization into
form
2^8 * 3^4 * 5^2 * 7?
Thank you.
- Rahul Kitture
HRI, Allahabad
From rahul.kitture at gmail.com Wed Feb 10 04:34:44 2016
From: rahul.kitture at gmail.com (Rahul Kitture)
Date: Wed, 10 Feb 2016 10:04:44 +0530
Subject: [GAP Forum] A question on factorization of an integer
Message-ID:
Dear Sir,
In some computations of orders of groups, which turn out to be large, I
wanted to see the prime factorization of the order. For example, I use
following kind of commands:
gap> g:=SymmetricGroup(10);; Size(g);
3628800
gap> Factors(3628800);
[ 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 5, 5, 7 ]
My question is, is there some command in GAP to get this factorization into
form
2^8 * 3^4 * 5^2 * 7?
Thank you.
- Rahul Kitture
HRI, Allahabad
From maasiru at yahoo.com Wed Feb 10 06:06:43 2016
From: maasiru at yahoo.com ([Muniru Asiru] maasiru@yahoo.com)
Date: Tue, 9 Feb 2016 22:06:43 -0800
Subject: [GAP Forum] A question on factorization of an integer
In-Reply-To:
Message-ID: <1455084403.23960.YahooMailMobile@web121505.mail.ne1.yahoo.com>
Yes. Partially. Use Collected
From maasiru at yahoo.com Wed Feb 10 06:06:43 2016
From: maasiru at yahoo.com ([Muniru Asiru] maasiru@yahoo.com)
Date: Tue, 9 Feb 2016 22:06:43 -0800
Subject: [GAP Forum] A question on factorization of an integer
In-Reply-To:
Message-ID: <1455084403.23960.YahooMailMobile@web121505.mail.ne1.yahoo.com>
Yes. Partially. Use Collected
From benjamin.sambale at gmail.com Wed Feb 10 06:28:38 2016
From: benjamin.sambale at gmail.com (Benjamin Sambale)
Date: Wed, 10 Feb 2016 07:28:38 +0100
Subject: [GAP Forum] A question on factorization of an integer
In-Reply-To:
References:
Message-ID: <56BAD896.1060703@gmail.com>
PrintFactorsInt
Am 10.02.2016 um 05:34 schrieb Rahul Kitture:
> Dear Sir,
> In some computations of orders of groups, which turn out to be large, I
> wanted to see the prime factorization of the order. For example, I use
> following kind of commands:
>
> gap> g:=SymmetricGroup(10);; Size(g);
> 3628800
> gap> Factors(3628800);
> [ 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 5, 5, 7 ]
>
> My question is, is there some command in GAP to get this factorization into
> form
>
> 2^8 * 3^4 * 5^2 * 7?
>
>
>
>
>
> Thank you.
>
> - Rahul Kitture
> HRI, Allahabad
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
From waghoba at gmail.com Wed Feb 10 06:28:49 2016
From: waghoba at gmail.com (Vinay Wagh)
Date: Wed, 10 Feb 2016 11:58:49 +0530
Subject: [GAP Forum] A question on factorization of an integer
In-Reply-To:
References:
Message-ID:
Here is what you need...
gap> PrintFactorsInt( 3628800);
VInay
On 10 February 2016 at 10:04, Rahul Kitture wrote:
> Dear Sir,
> In some computations of orders of groups, which turn out to be large, I
> wanted to see the prime factorization of the order. For example, I use
> following kind of commands:
>
> gap> g:=SymmetricGroup(10);; Size(g);
> 3628800
> gap> Factors(3628800);
> [ 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 5, 5, 7 ]
>
> My question is, is there some command in GAP to get this factorization into
> form
>
> 2^8 * 3^4 * 5^2 * 7?
>
>
>
>
>
> Thank you.
>
> - Rahul Kitture
> HRI, Allahabad
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From axyd0000 at gmail.com Wed Feb 10 06:51:02 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Wed, 10 Feb 2016 12:21:02 +0530
Subject: [GAP Forum] Documentation understanding of unary `Subgroup`
Message-ID:
Hi GAP forum members,
For the unary version of `Subgroup`, i am using it like this:
```
gap> g:=Group((1,2,3,4),(1,2));;
gap> f:=Subgroup(g)
```
Reading in the documentation it says:
> The unary version of Subgroup creates a (shell) subgroup that does
not even know generators but can be used to collect information about a
particular subgroup over time.
I don't understand what this means, can someone explain this? In
particular the statement "collect information over time", sounds very
unknown to me from GAP user perspective.
Thanks
Gaurav
From hulpke at math.colostate.edu Wed Feb 10 15:44:30 2016
From: hulpke at math.colostate.edu (Alexander Hulpke)
Date: Wed, 10 Feb 2016 08:44:30 -0700
Subject: [GAP Forum] Documentation understanding of unary `Subgroup`
In-Reply-To:
References:
Message-ID: <4B03061D-8626-4ED6-BCFA-AF664E9191F8@math.colostate.edu>
The unary version of `Subgroup? is intended to have a subgroup object that is going to be further specified in the course of an algorithm. E.g. if you do not know how to get generators of a Sylow subgroup, you could still have an object representing one and have this object store e.g. order, nilpotence etc.
There is currently little, if any, functionality that uses this.
Best,
Alexander Hulpke
-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke
From f.k.moftakhar at gmail.com Thu Feb 11 12:45:47 2016
From: f.k.moftakhar at gmail.com (fatemeh moftakhar)
Date: Thu, 11 Feb 2016 16:15:47 +0330
Subject: [GAP Forum] Error, exceeded the permitted memory
Message-ID:
Dear Forum
I have the following problem with GAP. Would you please help me?
gap> k(g52,D52);
Error, exceeded the permitted memory (`-o' command line option) in
rep := S.identity; called from
ElementsStabChain( StabChainMutable( G ) ) called from
AsSSortedList( coll ) called from
Elements( G ) called from
( )
called from read-eval loop at line 4 of *stdin*
you can 'return;'
brk>
How can I increase memory?
Best regards
Fatemeh
--
Regards;
Miss Fatemeh Moftakhar
PhD Candidate,
Department of Pure Mathematics,
Faculty of Mathematical Sciences,
University of Kashan, Kashan, Iran
From colva at mcs.st-and.ac.uk Thu Feb 11 15:15:47 2016
From: colva at mcs.st-and.ac.uk (Colva Roney-Dougal)
Date: Thu, 11 Feb 2016 15:15:47 +0000
Subject: [GAP Forum] Groups St Andrews 2017 in Birmingham
Message-ID:
Dear Colleagues,
The organisers of Groups St Andrews 2017 in Birmingham are pleased to be able to announce the speakers invited to the conference.
Main Speakers:
Michael Aschbacher (California Institute of Technology)
Radha Kessar (City University, London)
Pierre-Emmanuel Caprace (Universite Catholique de Louvain)
Gunter Malle (TU Kaiserslautern)
Plenary Speakers:
Tim Burness (University of Bristol)
Vincent Guirardel (Universite de Rennes 1)
Harald Helfgott (University of Gottingen)
Andrei Jaikin-Zapirain (Universidad Autonoma de Madrid)
Donna Testerman (Ecole Polytechnique Federale de Lausanne)
The arrival day for the conference is Saturday 5th August 2017 and the departure day is Sunday 13th August 2017. The talks will take place from 6th to 12th August inclusive.
The conference website is available at the following link: http://www.groupsstandrews.org/2017/index.shtml
We encourage those interested in attending the conference to register on the website to receive further updates on the conference.
We hope that you will be able to join us in 2017.
Conference Organisers:
Colin Campbell, Chris Parker, Martyn Quick, Edmund Robertson & Colva Roney-Dougal
From alexk at mcs.st-and.ac.uk Thu Feb 11 22:14:40 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Thu, 11 Feb 2016 22:14:40 +0000
Subject: [GAP Forum] Error, exceeded the permitted memory
In-Reply-To:
References:
Message-ID: <4443A4ED-CEE7-46A9-8AED-CF6DB49DD131@mcs.st-andrews.ac.uk>
Dear Fatemeh,
Please see 6.2: My calculation does not finish (or GAP runs out of memory)
from the GAP F.A.Q: http://gap-system.org/Faq/faq.html#6.2
If you will need further help, I suggest to ask GAP Support:
http://gap-system.org/Contacts/People/supportgroup.html
Hope this helps
Alexander
> On 11 Feb 2016, at 12:45, fatemeh moftakhar wrote:
>
> Dear Forum
> I have the following problem with GAP. Would you please help me?
>
> gap> k(g52,D52);
> Error, exceeded the permitted memory (`-o' command line option) in
> rep := S.identity; called from
> ElementsStabChain( StabChainMutable( G ) ) called from
> AsSSortedList( coll ) called from
> Elements( G ) called from
> ( )
> called from read-eval loop at line 4 of *stdin*
> you can 'return;'
> brk>
>
> How can I increase memory?
>
> Best regards
> Fatemeh
> --
> Regards;
> Miss Fatemeh Moftakhar
> PhD Candidate,
> Department of Pure Mathematics,
> Faculty of Mathematical Sciences,
> University of Kashan, Kashan, Iran
From f.k.moftakhar at gmail.com Fri Feb 12 06:36:25 2016
From: f.k.moftakhar at gmail.com (fatemeh moftakhar)
Date: Fri, 12 Feb 2016 10:06:25 +0330
Subject: [GAP Forum] Error, exceeded the permitted memory
In-Reply-To: <4443A4ED-CEE7-46A9-8AED-CF6DB49DD131@mcs.st-andrews.ac.uk>
References:
<4443A4ED-CEE7-46A9-8AED-CF6DB49DD131@mcs.st-andrews.ac.uk>
Message-ID:
Dear Professor Konovalov
Thank you very much for your response.
I used the following commands and my problem is solved.
./gap.sh -m 4g
and when the following error was showed, I just type return;
exceeded the permitted memory (-o command line option)
Your response helps me.
Thanks a lot
Fatemeh Moftakhar
On Fri, Feb 12, 2016 at 1:44 AM, Alexander Konovalov wrote:
> Dear Fatemeh,
>
> Please see 6.2: My calculation does not finish (or GAP runs out of memory)
> from the GAP F.A.Q: http://gap-system.org/Faq/faq.html#6.2
>
> If you will need further help, I suggest to ask GAP Support:
> http://gap-system.org/Contacts/People/supportgroup.html
>
> Hope this helps
> Alexander
>
>
>
> > On 11 Feb 2016, at 12:45, fatemeh moftakhar
> wrote:
> >
> > Dear Forum
> > I have the following problem with GAP. Would you please help me?
> >
> > gap> k(g52,D52);
> > Error, exceeded the permitted memory (`-o' command line option) in
> > rep := S.identity; called from
> > ElementsStabChain( StabChainMutable( G ) ) called from
> > AsSSortedList( coll ) called from
> > Elements( G ) called from
> > ( )
> > called from read-eval loop at line 4 of *stdin*
> > you can 'return;'
> > brk>
> >
> > How can I increase memory?
> >
> > Best regards
> > Fatemeh
> > --
> > Regards;
> > Miss Fatemeh Moftakhar
> > PhD Candidate,
> > Department of Pure Mathematics,
> > Faculty of Mathematical Sciences,
> > University of Kashan, Kashan, Iran
>
--
Regards;
Miss Fatemeh Moftakhar
PhD Candidate,
Department of Pure Mathematics,
Faculty of Mathematical Sciences,
University of Kashan, Kashan, Iran
From pjc at mcs.st-andrews.ac.uk Sat Feb 13 20:24:50 2016
From: pjc at mcs.st-andrews.ac.uk (Peter Cameron)
Date: Sat, 13 Feb 2016 20:24:50 -0000 (UTC)
Subject: [GAP Forum] A question about Action
Message-ID:
Dear GAP forum,
It seems that GAP can find representatives for all systems of minimal blocks
of imprimitivity for an arbitrary group action, but all blocks only for a
permutation group (and there seems no easy way to get all maximal blocks).
I have tried to get around this as follows. G is a group acting on O (which
is actually an orbit on 2-subsets of [1..n]). I do the following:
GG:=Action(G,O,OnSets);
BB:=AllBlocks(GG);
B:=List(BB,x->List(x,y->O[y]));
This assumes that the Action maps each element of O to its position in the
list, and I can't find a guarantee to this effect in the manual. Can I rely
on this?
Thanks for any advice.
Peter Cameron.
--
This email address will stop working sometime soon. Please use the address
pjc20 at st-andrews.ac.uk instead.
From sl4 at st-andrews.ac.uk Sat Feb 13 21:11:28 2016
From: sl4 at st-andrews.ac.uk (Stephen Linton)
Date: Sat, 13 Feb 2016 21:11:28 +0000
Subject: [GAP Forum] A question about Action
In-Reply-To:
References:
Message-ID:
> On 13 Feb 2016, at 20:24, Peter Cameron wrote:
>
> Dear GAP forum,
>
> It seems that GAP can find representatives for all systems of minimal blocks
> of imprimitivity for an arbitrary group action, but all blocks only for a
> permutation group (and there seems no easy way to get all maximal blocks).
>
You can build up from minimal blocks recursively, of course. Take the action on the blocks of a minimal block
system and find the minimal blocks there, they correspond to non-minimal block systems for the original action, etc.
> I have tried to get around this as follows. G is a group acting on O (which
> is actually an orbit on 2-subsets of [1..n]). I do the following:
>
> GG:=Action(G,O,OnSets);
> BB:=AllBlocks(GG);
> B:=List(BB,x->List(x,y->O[y]));
>
> This assumes that the Action maps each element of O to its position in the
> list, and I can't find a guarantee to this effect in the manual. Can I rely
> on this?
I believe so, although this is (at least) a documentation failing). The manual does say:
40.3-2 Action homomorphisms
See ActionHomomorphism (41.7-1).
The calculation of images is determined by the acting function used and -for large domains- is often dominated by the search for the position of an
image in a list of the domain elements. This can be improved by sorting this list if an efficient method for \< (31.11-1) to compare elements of the
domain is available.
which strongly suggests to me that it is retaining the given order for the domain.
Steve
>
> Thanks for any advice.
>
> Peter Cameron.
>
>
>
> --
> This email address will stop working sometime soon. Please use the address
> pjc20 at st-andrews.ac.uk instead.
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From jacob.benoit.1 at gmail.com Sat Feb 13 23:57:02 2016
From: jacob.benoit.1 at gmail.com (Benoit Jacob)
Date: Sat, 13 Feb 2016 18:57:02 -0500
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
Message-ID:
Hello,
What would be a good approach to obtain a parametrization of the set of all
rank-1 matrices in a given subspace of matrices M_n(F), where F is a finite
field?
It seems that what I'm looking for is equivalent to Maple's Rank1Elements()
function
.
Thanks,
Benoit
From hulpke at math.colostate.edu Mon Feb 15 16:53:47 2016
From: hulpke at math.colostate.edu (Alexander Hulpke)
Date: Mon, 15 Feb 2016 09:53:47 -0700
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
In-Reply-To:
References:
Message-ID:
> On Feb 13, 2016, at 4:57 PM, Benoit Jacob wrote:
>
> Hello,
>
> What would be a good approach to obtain a parametrization of the set of all
> rank-1 matrices in a given subspace of matrices M_n(F), where F is a finite
> field?
If you want nxm matrices over a field k, why not pick a random nonzero vector v\in k^n and a random normed (i.e. first nonzero coefficient is one) vector w\in k^m and form the (matrix) product v * w^T. I think this gives you a perfect parameterization via parameterizing v and w.
Best,
Alexander Hulpke
-- Colorado State University, Department of Mathematics,
Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
http://www.math.colostate.edu/~hulpke
From jacob.benoit.1 at gmail.com Mon Feb 15 16:54:46 2016
From: jacob.benoit.1 at gmail.com (Benoit Jacob)
Date: Mon, 15 Feb 2016 11:54:46 -0500
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
In-Reply-To:
References:
Message-ID:
Hi Alexander,
That would give me the set of all rank-1 matrices. I want the set of those
rank-1 matrices that belong to some given linear subspace of matrices,
given e.g. as the span of a finite family of matrices.
Cheers,
Benoit
2016-02-15 11:53 GMT-05:00 Alexander Hulpke :
>
> > On Feb 13, 2016, at 4:57 PM, Benoit Jacob
> wrote:
> >
> > Hello,
> >
> > What would be a good approach to obtain a parametrization of the set of
> all
> > rank-1 matrices in a given subspace of matrices M_n(F), where F is a
> finite
> > field?
>
> If you want nxm matrices over a field k, why not pick a random nonzero
> vector v\in k^n and a random normed (i.e. first nonzero coefficient is one)
> vector w\in k^m and form the (matrix) product v * w^T. I think this gives
> you a perfect parameterization via parameterizing v and w.
>
> Best,
>
> Alexander Hulpke
>
> -- Colorado State University, Department of Mathematics,
> Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
> email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
> http://www.math.colostate.edu/~hulpke
>
>
>
From hulpke at math.colostate.edu Mon Feb 15 21:07:24 2016
From: hulpke at math.colostate.edu (Alexander Hulpke)
Date: Mon, 15 Feb 2016 14:07:24 -0700
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
In-Reply-To:
References:
Message-ID: <30AF9A7E-0F60-4C5D-B63E-D55BB37EB625@math.colostate.edu>
Dear Benoit,
Ah ? within a subspace will give you polynomial equations (all 2x2 subdeterminants=0) in the coefficients of a linear combination, and at least in principle this can be done with Groebner bases (i.e. you get rank <=1, but rank 0 is easily eliminated.)
For example (using the appended function) for the standard basis of Q^{3\times 4}:
gap> b:=BasisVectors(Basis(MatrixSpace(Rationals,3,4)));;
gap> e:=Rank1Equations(b);
[ x_1*x_6-x_2*x_5, x_1*x_7-x_3*x_5, x_1*x_8-x_4*x_5, x_2*x_7-x_3*x_6,
x_2*x_8-x_4*x_6, x_3*x_8-x_4*x_7, x_1*x_10-x_2*x_9, x_1*x_11-x_3*x_9,
x_1*x_12-x_4*x_9, x_2*x_11-x_3*x_10, x_2*x_12-x_4*x_10, x_3*x_12-x_4*x_11,
x_5*x_10-x_6*x_9, x_5*x_11-x_7*x_9, x_5*x_12-x_8*x_9, x_6*x_11-x_7*x_10,
x_6*x_12-x_8*x_10, x_7*x_12-x_8*x_11 ]
gap> ReducedGroebnerBasis(e,MonomialLexOrdering());
[ x_7*x_12-x_8*x_11, x_6*x_12-x_8*x_10, x_6*x_11-x_7*x_10, x_5*x_12-x_8*x_9,
x_5*x_11-x_7*x_9, x_5*x_10-x_6*x_9, x_3*x_12-x_4*x_11, x_3*x_8-x_4*x_7,
x_2*x_12-x_4*x_10, x_2*x_11-x_3*x_10, x_2*x_8-x_4*x_6, x_2*x_7-x_3*x_6,
x_1*x_12-x_4*x_9, x_1*x_11-x_3*x_9, x_1*x_10-x_2*x_9, x_1*x_8-x_4*x_5,
x_1*x_7-x_3*x_5, x_1*x_6-x_2*x_5 ]
So x_7 =x_8*x_11/x_12 (and case for x_12=0) etc. and you can build an (ugly) parameterization from these.
(Alternatively one could try to use \sum_c_i M_i=v\cdot w^T with v and w given by extra variables that are to be eliminated. This will yield the same Groebner basi after variable elimination.)
Best,
Alexander
Rank1Equations:=function(mats)
local l,f,r,vars,n,m,c,d,eqs;
l:=Length(mats);
f:=DefaultFieldOfMatrix(mats[1]);
r:=PolynomialRing(f,l);
vars:=IndeterminatesOfPolynomialRing(r);
n:=Length(mats[1]);
m:=Length(mats[1][1]);
eqs:=[];
for c in Combinations([1..n],2) do
for d in Combinations([1..m],2) do
Add(eqs,
Sum([1..l],x->vars[x]*mats[x][c[1]][d[1]])
*Sum([1..l],x->vars[x]*mats[x][c[2]][d[2]])
-Sum([1..l],x->vars[x]*mats[x][c[1]][d[2]])
*Sum([1..l],x->vars[x]*mats[x][c[2]][d[1]]));
od;
od;
return eqs;
end;
From dmitrii.pasechnik at cs.ox.ac.uk Mon Feb 15 21:19:07 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dima Pasechnik)
Date: Mon, 15 Feb 2016 21:19:07 +0000
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
In-Reply-To:
References:
Message-ID: <20160215211907.GB20273@dimpase.cs.ox.ac.uk>
Hi Benoit,
On Mon, Feb 15, 2016 at 11:54:46AM -0500, Benoit Jacob wrote:
> That would give me the set of all rank-1 matrices. I want the set of those
> rank-1 matrices that belong to some given linear subspace of matrices,
> given e.g. as the span of a finite family of matrices.
this is a hard problem. One can write down
a system of polynomial equations specifying the matrices you are interested in.
Let A=sum_k x_k A_k be the matrix of linear forms in variables x_k,
and A_k span your subspace. You need to set all the 2x2 minors of A to 0,
giving you a system of quadratic equations in x_k. Its solutions specify
the rank 1 matrices in your subspace.
It does not seem likely that there is a nice parametrisation of this set.
Hope this helps,
Dima
> Cheers,
> Benoit
>
> 2016-02-15 11:53 GMT-05:00 Alexander Hulpke :
>
> >
> > > On Feb 13, 2016, at 4:57 PM, Benoit Jacob
> > wrote:
> > >
> > > Hello,
> > >
> > > What would be a good approach to obtain a parametrization of the set of
> > all
> > > rank-1 matrices in a given subspace of matrices M_n(F), where F is a
> > finite
> > > field?
> >
> > If you want nxm matrices over a field k, why not pick a random nonzero
> > vector v\in k^n and a random normed (i.e. first nonzero coefficient is one)
> > vector w\in k^m and form the (matrix) product v * w^T. I think this gives
> > you a perfect parameterization via parameterizing v and w.
> >
> > Best,
> >
> > Alexander Hulpke
> >
> > -- Colorado State University, Department of Mathematics,
> > Weber Building, 1874 Campus Delivery, Fort Collins, CO 80523-1874, USA
> > email: hulpke at math.colostate.edu, Phone: ++1-970-4914288
> > http://www.math.colostate.edu/~hulpke
> >
> >
> >
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From jacob.benoit.1 at gmail.com Mon Feb 15 21:53:11 2016
From: jacob.benoit.1 at gmail.com (Benoit Jacob)
Date: Mon, 15 Feb 2016 16:53:11 -0500
Subject: [GAP Forum] Find rank-1 matrices in given subspace of matrices
In-Reply-To: <30AF9A7E-0F60-4C5D-B63E-D55BB37EB625@math.colostate.edu>
References:
<30AF9A7E-0F60-4C5D-B63E-D55BB37EB625@math.colostate.edu>
Message-ID:
Many thanks, Alexander and Dima, for your replies!
I was missing the key idea that rank one is charactized by the nullness of
all 2x2 minors.
Thanks also Alexander for the nice implementation!
Cheers,
Benoit
2016-02-15 16:07 GMT-05:00 Alexander Hulpke :
> Dear Benoit,
>
> Ah ? within a subspace will give you polynomial equations (all 2x2
> subdeterminants=0) in the coefficients of a linear combination, and at
> least in principle this can be done with Groebner bases (i.e. you get rank
> <=1, but rank 0 is easily eliminated.)
>
> For example (using the appended function) for the standard basis of
> Q^{3\times 4}:
>
> gap> b:=BasisVectors(Basis(MatrixSpace(Rationals,3,4)));;
> gap> e:=Rank1Equations(b);
> [ x_1*x_6-x_2*x_5, x_1*x_7-x_3*x_5, x_1*x_8-x_4*x_5, x_2*x_7-x_3*x_6,
> x_2*x_8-x_4*x_6, x_3*x_8-x_4*x_7, x_1*x_10-x_2*x_9, x_1*x_11-x_3*x_9,
> x_1*x_12-x_4*x_9, x_2*x_11-x_3*x_10, x_2*x_12-x_4*x_10,
> x_3*x_12-x_4*x_11,
> x_5*x_10-x_6*x_9, x_5*x_11-x_7*x_9, x_5*x_12-x_8*x_9, x_6*x_11-x_7*x_10,
> x_6*x_12-x_8*x_10, x_7*x_12-x_8*x_11 ]
> gap> ReducedGroebnerBasis(e,MonomialLexOrdering());
> [ x_7*x_12-x_8*x_11, x_6*x_12-x_8*x_10, x_6*x_11-x_7*x_10,
> x_5*x_12-x_8*x_9,
> x_5*x_11-x_7*x_9, x_5*x_10-x_6*x_9, x_3*x_12-x_4*x_11, x_3*x_8-x_4*x_7,
> x_2*x_12-x_4*x_10, x_2*x_11-x_3*x_10, x_2*x_8-x_4*x_6, x_2*x_7-x_3*x_6,
> x_1*x_12-x_4*x_9, x_1*x_11-x_3*x_9, x_1*x_10-x_2*x_9, x_1*x_8-x_4*x_5,
> x_1*x_7-x_3*x_5, x_1*x_6-x_2*x_5 ]
>
> So x_7 =x_8*x_11/x_12 (and case for x_12=0) etc. and you can build an
> (ugly) parameterization from these.
>
> (Alternatively one could try to use \sum_c_i M_i=v\cdot w^T with v and w
> given by extra variables that are to be eliminated. This will yield the
> same Groebner basi after variable elimination.)
>
> Best,
>
> Alexander
>
>
>
> Rank1Equations:=function(mats)
> local l,f,r,vars,n,m,c,d,eqs;
> l:=Length(mats);
> f:=DefaultFieldOfMatrix(mats[1]);
> r:=PolynomialRing(f,l);
> vars:=IndeterminatesOfPolynomialRing(r);
> n:=Length(mats[1]);
> m:=Length(mats[1][1]);
> eqs:=[];
> for c in Combinations([1..n],2) do
> for d in Combinations([1..m],2) do
> Add(eqs,
> Sum([1..l],x->vars[x]*mats[x][c[1]][d[1]])
> *Sum([1..l],x->vars[x]*mats[x][c[2]][d[2]])
> -Sum([1..l],x->vars[x]*mats[x][c[1]][d[2]])
> *Sum([1..l],x->vars[x]*mats[x][c[2]][d[1]]));
> od;
> od;
> return eqs;
> end;
>
>
>
>
>
>
>
From axyd0000 at gmail.com Fri Feb 26 09:17:42 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Fri, 26 Feb 2016 14:47:42 +0530
Subject: [GAP Forum] Using GAP online
Message-ID:
Hi GAP members
Is there any way i can use GAP online? I know that i can use Sage online
(for using GAP functionality).
But is there any way i can use GAP alone?
Thanks
Gaurav Dhingra
From dmitrii.pasechnik at cs.ox.ac.uk Fri Feb 26 09:55:26 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dima Pasechnik)
Date: Fri, 26 Feb 2016 09:55:26 +0000
Subject: [GAP Forum] Using GAP online
In-Reply-To:
References:
Message-ID: <20160226095526.GA1586@dimpase.cs.ox.ac.uk>
On Fri, Feb 26, 2016 at 02:47:42PM +0530, Gaurav Dhingra wrote:
> Is there any way i can use GAP online? I know that i can use Sage
> online (for using GAP functionality).
you most probably refer to cloud.sagemath.com, right?
> But is there any way i can use GAP alone?
in a cloud.sagemath.com project, you can open a terminal
and run GAP at the shell prompt.
i.e. just type 'gap' at the '$' prompt and hit 'Enter'. Upon opening a terminal, you
will see something like the following:
(and then I started GAP there, as you see below)
???????????????????????????????????????????????????????????????????????????????????
? Welcome to the SageMathCloud Terminal Environment ?
? ?
? Software: sage, R, ipython, gap, gp, git, latexmk, isympy, java, julia, octave, ?
? vim, emacs, nano, gcc, clang, pdflatex, xetex, node, convert, mc, htop, atop, ...?
? ???????????????????????????
? Anaconda Python environment: anaconda3 ? Usage: type command in ?
? ... and to exit Anaconda: exit-anaconda ? then hit the return key ?
? ???????????????????????????
? Learn about the Linux Bash terminal: http://ryanstutorials.net/linuxtutorial/ ?
? Are there any problems or is something missing? email us at help at sagemath.com ?
????????????????????????????????????????????????????????????????????????????????????
~$
~$ gap
????????? GAP, Version 4.7.8 of 09-Jun-2015 (free software, GPL)
? GAP ? http://www.gap-system.org
????????? Architecture: x86_64-unknown-linux-gnu-gcc-default64
Libs used: gmp, readline
Loading the library and packages ...
Components: trans 1.0, prim 2.1, small* 1.0, id* 1.0
Packages: Alnuth 3.0.0, AtlasRep 1.5.0, AutPGrp 1.6, CTblLib 1.2.2, FactInt 1.5.3, GAPDoc 1.5.1, LAGUNA 3.7.0, Polycyclic 2.11, TomLib 1.2.5
Try '?help' for help. See also '?copyright' and '?authors'
Apart from the packages listed, there is a dozen other GAP packages that are installed, such as
GRAPE, which you could load using LoadPackage
HTH
Dima
>
> Thanks
> Gaurav Dhingra
>
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From suskudar at gmail.com Fri Feb 26 10:20:47 2016
From: suskudar at gmail.com (=?utf-8?Q?S=C3=BCmeyra_Bedir?=)
Date: Fri, 26 Feb 2016 12:20:47 +0200
Subject: [GAP Forum] Using GAP online
In-Reply-To:
References:
Message-ID:
Hi,
You may try this; http://artin.nuigalway.ie/gap_calculator/gap_terminal
The issue was discussed before and above was a temporary solution,
S?meyra Bedir
26 ?ub 2016 tarihinde 11:17 saatinde, Gaurav Dhingra ?unlar? yazd?:
> Hi GAP members
>
> Is there any way i can use GAP online? I know that i can use Sage online (for using GAP functionality).
> But is there any way i can use GAP alone?
>
> Thanks
> Gaurav Dhingra
>
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From alexk at mcs.st-and.ac.uk Fri Feb 26 16:42:19 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Fri, 26 Feb 2016 16:42:19 +0000
Subject: [GAP Forum] GAP 4.8.2 release announcement
Message-ID: <77E52CF0-802D-4178-A470-ED4F514633AD@mcs.st-andrews.ac.uk>
Dear all,
This is to announce the release of GAP 4.8.2, which could be downloaded from
http://www.gap-system.org/Releases/
This is the first major release made from the GAP repository on GitHub
(at https://github.com/gap-system/gap). An overview of the most
significant ones is provided below. A more detailed version with
hyperlinks is available on the GAP website here:
http://www.gap-system.org/Manuals/doc/changes/chap2.htm
New features:
* Added support for profiling which tracks how much time in spent on
each line of GAP code. This can be used to show where code is spending
a long time and also check which lines of code are even executed.
* Added _ability_ to install (in the library or packages) methods for
accessing lists using multiple indices and indexing into lists using
indices other than positive small integers. Such methods could allow
you, for example, to define behaviour for expressions like
m[1,2];
m[1,2,3] := x;
IsBound(m["a","b",Z(7)]);
Unbind(m[1][2,3])
* Added support for partially variadic functions to allow function
expressions like
function(a,b,c,x...) ... end;
which would require at least three arguments and assign the first three
to a, b and c and then a list containing any remaining ones to x.
The former special meaning of the argument arg is still supported and
is now equivalent to function(arg...), so no changes in the existing code
are required.
* Introduced CallWithTimeout and CallWithTimeoutList to call a function
with a limit on the CPU time it can consume. This functionality may not
be available on all systems and you should check GAPInfo.TimeoutsSupported
before using this functionality.
* GAP now displays the filename and line numbers of statements in
backtraces when entering the break loop.
Improved and extended functionality:
* Method tracing shows the filename and line of function during tracing.
* TraceAllMethods and UntraceAllMethods to turn on and off tracing all
methods in GAP. Also, for the uniform approach UntraceImmediateMethods
has been added as an equivalent of TraceImmediateMethods(false)
* Performance improvements for dictionaries.
* Improved methods for symmetric and alternating groups in the "natural"
representations.
* Package authors may optionally specify the source code repository,
issue tracker and support email address for their package using new
components in the PackageInfo.g file.
Changed functionality:
* As a preparation for the future developments to support multithreading,
some language extensions from the HPC-GAP project were backported to the
GAP library to help to unify the codebase of both GAP 4 and HPC-GAP. In
particular, this introduces new keywords "atomic", "readonly" and
"readwrite".
* There was inconsistent use of the following properties of semigroups:
IsGroupAsSemigroup, IsMonoidAsSemigroup, and IsSemilatticeAsSemigroup,
which has been corrected.
* ReadTest became obsolete and for backwards compatibility is replaced by
Test with the option to compare the output up to whitespaces.
* The function ErrorMayQuit, which differs from Error by not allowing
execution to continue, has been renamed to ErrorNoReturn.
Fixed bugs:
* Problems arising when an element of an extension field was assigned
into a compressed matrix.
* Problems in the Fitting-free code and code inheriting PCGS.
* A bug that caused a break loop in the computation of the Hall subgroup
for groups having a trivial Fitting subgroup.
* Including a break or continue statement in a function body but not in a
loop now gives a syntax error instead of failing at run time.
* GroupGeneralMappingByImages now verifies that that image of a mapping is
contained in its range. This may sometimes slow down construction of
mappings. If this is a problem, and you are sure the image of the mapping
will be contained in the range, use GroupGeneralMappingByImagesNC instead.
* Fixed a bug in caching the degree of transformation that could lead to a
non-identity transformation accidentally changing its value to the identity
transformation.
* Fixed the problem with using Windows default browser as a help viewer
using SetHelpViewer("browser");.
New and updated packages since GAP 4.7.8
At the time of the release of GAP 4.7.8 there were 119 packages
redistributed with GAP. New packages that have been added to the
redistribution since the release of GAP 4.7.8 are:
* CAP (Categories, Algorithms, Programming) package by Sebastian Gutsche,
Sebastian Posur and ?ystein Skarts?terhagen, together with three associated
packages GeneralizedMorphismsForCAP, LinearAlgebraForCAP] and
ModulePresentationsForCAP] (all three - by Sebastian Gutsche and Sebastian
Posur).
* Digraphs by Jan De Beule, Julius Jonu?as, James Mitchell, Michael Torpey
and Wilf Wilson, which provides functionality to work with graphs, digraphs,
and multidigraphs.
* FinInG package by John Bamberg, Anton Betten, Philippe Cara, Jan De Beule,
Michel Lavrauw and Max Neunh?ffer for computation in Finite Incidence Geometry.
* HeLP package by Andreas B?chle and Leo Margolis, which computes constraints
on partial augmentations of torsion units in integral group rings using a
method developed by Luthar, Passi and Hertweck.
* matgrp package by Alexander Hulpke, which provides an interface to the
solvable radical functionality for matrix groups, building on constructive
recognition.
* NormalizInterface package by Sebastian Gutsche, Max Horn and Christof S?ger,
which provides a GAP interface to Normaliz, enabling direct access to the
complete functionality of Normaliz, such as computations in affine monoids,
vector configurations, lattice polytopes, and rational cones.
* profiling package by Christopher Jefferson for transforming profiles
produced by ProfileLineByLine and CoverageLineByLine into a human-readable
form.
* Utils package by Sebastian Gutsche, Stefan Kohl and Christopher Wensley,
which provides a collection of utility functions gleaned from many packages.
* XModAlg package by Zekeriya Arvasi and Alper Odabas, which provides a
collection of functions for computing with crossed modules and Cat1-algebras
and morphisms of these structures.
In addition, a number of packages previously redistributed with GAP has been
updated.
We encourage all users to upgrade to GAP 4.8.2. If you need any help or
would like to report any problems, please do not hesitate to contact us
at support at gap-system.org or submit new issues on GitHub:
https://github.com/gap-system/gap/issues
Wishing you fun and success using GAP,
The GAP Group
From alexk at mcs.st-and.ac.uk Fri Feb 26 16:50:18 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Fri, 26 Feb 2016 16:50:18 +0000
Subject: [GAP Forum] GAP 4.8.2 release announcement
In-Reply-To: <77E52CF0-802D-4178-A470-ED4F514633AD@mcs.st-andrews.ac.uk>
References: <77E52CF0-802D-4178-A470-ED4F514633AD@mcs.st-andrews.ac.uk>
Message-ID: <0A347B6A-83DD-4D08-89F6-E39FC5903856@mcs.st-andrews.ac.uk>
P.S. Only if you are using Windows:
1) We strongly advise to use the executable Windows installer for GAP:
http://www.gap-system.org/pub/gap/gap48/exe/gap4r8p2_2016_02_20-18_51.exe
which will update all bat-files automatically. Note that the path to the
GAP directory should not contain spaces. For example, you may install it
in C:\gap4r8(default), D:\gap4r8p2 or C:\Math\GAP\gap4r8, but you must
not install it in a directory named like C:\Program files\gap4r8 or
C:\Users\alice\My Documents\gap4r8 etc.
2) In GAP 4.8.2 for Windows, there are no compiled binaries for the Browse
package and there is no readline support. We hope to fix this in GAP 4.8.3
3) There is an experimental 64-bit version of GAP for Windows, also available
from http://www.gap-system.org/Releases/. As it is experimental, some packages
may not work there. To install it, you need to unzip the archive and adjust
*.bat files manually. We will be interested to hear any feedback about its
usability.
Best wishes
Alexander
> On 26 Feb 2016, at 16:42, Alexander Konovalov wrote:
>
> Dear all,
>
> This is to announce the release of GAP 4.8.2, which could be downloaded from
>
> http://www.gap-system.org/Releases/
>
> This is the first major release made from the GAP repository on GitHub
> (at https://github.com/gap-system/gap). An overview of the most
> significant ones is provided below. A more detailed version with
> hyperlinks is available on the GAP website here:
>
> http://www.gap-system.org/Manuals/doc/changes/chap2.htm
From benjamin.sambale at gmail.com Sat Feb 27 11:04:13 2016
From: benjamin.sambale at gmail.com (Benjamin Sambale)
Date: Sat, 27 Feb 2016 12:04:13 +0100
Subject: [GAP Forum] installation problems with 4.8.2
Message-ID: <56D182AD.1000508@gmail.com>
Dear GAP people,
I installed the new release and the compiling process seemed fine to me
(using a recent arch linux version). When I started, I got the error
that /usr/local/gap4r8/pkg/PolymakeInterface/PackageInfo.g is unreadable
or does not exist (notice that it is a new package). However, the file
does exist, but I found out that most files are owned by 50009 whoever
that is (this was never a problem in previous versions). So I made this
particular file readable for group users. Now I can start GAP and also
the packages load, but the help system is broken:
gap> ?help
Error, no method found! For debugging hints type ?Recovery from
NoMethodFound
Error, no 1st choice method found for `ReadLine' on 1 arguments
I have no idea what is going on. Any ideas?
Best wishes,
Benjamin
From alexk at mcs.st-and.ac.uk Sat Feb 27 13:09:52 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Sat, 27 Feb 2016 13:09:52 +0000
Subject: [GAP Forum] installation problems with 4.8.2
In-Reply-To: <56D182AD.1000508@gmail.com>
References: <56D182AD.1000508@gmail.com>
Message-ID: <4E6E1B40-8968-4B57-845C-CDE10B25A5E1@mcs.st-andrews.ac.uk>
Dear Benjamin, dear GAP Forum,
Thank you for reporting this - we have heard this three times so far,
from users installing GAP as root outside their home directories (this
will not affect you if you install and run GAP as the same user).
What happened is that several packages were released with files not
having appropriate permissions. This will be fixed in GAP 4.8.3. In
the meantime, please use the following fix to make all package files
world-readable:
cd gap4r8 # or whatever the name is
chmod -R a+r pkg
(we suggest to call it on the whole 'pkg' subdirectory rather than on
individual packages involved, just in case).
Apologies for any inconveniences,
Alexander
P.S. The help system reads information about known help books,
including package manuals, so this is an instance of the same
problem with permissions. Calling `chmod -R a+r pkg` on the whole
pkg directory should fix all problems at once.
> On 27 Feb 2016, at 11:04, Benjamin Sambale wrote:
>
> Dear GAP people,
>
> I installed the new release and the compiling process seemed fine to me (using a recent arch linux version). When I started, I got the error that /usr/local/gap4r8/pkg/PolymakeInterface/PackageInfo.g is unreadable or does not exist (notice that it is a new package). However, the file does exist, but I found out that most files are owned by 50009 whoever that is (this was never a problem in previous versions). So I made this particular file readable for group users. Now I can start GAP and also the packages load, but the help system is broken:
>
> gap> ?help
> Error, no method found! For debugging hints type ?Recovery from NoMethodFound
> Error, no 1st choice method found for `ReadLine' on 1 arguments
>
> I have no idea what is going on. Any ideas?
>
> Best wishes,
> Benjamin
From benjamin.sambale at gmail.com Sat Feb 27 18:33:05 2016
From: benjamin.sambale at gmail.com (Benjamin Sambale)
Date: Sat, 27 Feb 2016 19:33:05 +0100
Subject: [GAP Forum] installation problems with 4.8.2
In-Reply-To: <4E6E1B40-8968-4B57-845C-CDE10B25A5E1@mcs.st-andrews.ac.uk>
References: <56D182AD.1000508@gmail.com>
<4E6E1B40-8968-4B57-845C-CDE10B25A5E1@mcs.st-andrews.ac.uk>
Message-ID: <56D1EBE1.7070209@gmail.com>
Dear Alexander,
many thanks! Problem solved.
Benjamin
Am 27.02.2016 um 14:09 schrieb Alexander Konovalov:
> Dear Benjamin, dear GAP Forum,
>
> Thank you for reporting this - we have heard this three times so far,
> from users installing GAP as root outside their home directories (this
> will not affect you if you install and run GAP as the same user).
>
> What happened is that several packages were released with files not
> having appropriate permissions. This will be fixed in GAP 4.8.3. In
> the meantime, please use the following fix to make all package files
> world-readable:
>
> cd gap4r8 # or whatever the name is
> chmod -R a+r pkg
>
> (we suggest to call it on the whole 'pkg' subdirectory rather than on
> individual packages involved, just in case).
>
> Apologies for any inconveniences,
> Alexander
>
> P.S. The help system reads information about known help books,
> including package manuals, so this is an instance of the same
> problem with permissions. Calling `chmod -R a+r pkg` on the whole
> pkg directory should fix all problems at once.
>
>
>> On 27 Feb 2016, at 11:04, Benjamin Sambale wrote:
>>
>> Dear GAP people,
>>
>> I installed the new release and the compiling process seemed fine to me (using a recent arch linux version). When I started, I got the error that /usr/local/gap4r8/pkg/PolymakeInterface/PackageInfo.g is unreadable or does not exist (notice that it is a new package). However, the file does exist, but I found out that most files are owned by 50009 whoever that is (this was never a problem in previous versions). So I made this particular file readable for group users. Now I can start GAP and also the packages load, but the help system is broken:
>>
>> gap> ?help
>> Error, no method found! For debugging hints type ?Recovery from NoMethodFound
>> Error, no 1st choice method found for `ReadLine' on 1 arguments
>>
>> I have no idea what is going on. Any ideas?
>>
>> Best wishes,
>> Benjamin
>
>
>
From sara.yaftian at gmail.com Wed Mar 2 06:03:19 2016
From: sara.yaftian at gmail.com (Sara Yaftian)
Date: Wed, 2 Mar 2016 09:33:19 +0330
Subject: [GAP Forum] Boolean matrix
Message-ID:
Dear GAP Forum
I need a m by n Boolean matrix for saving memory in my works. I know
A:=NullMat(m,n);
is a Null matrix but I need boolean version. I wrote the following code
B:=[];
for i in [1..3] do
Add(B,false);
od;
A:=[B];
for j in [1..3] do
Add(A,B);
od;
this is the output:
gap> A;
[ [ false, false, false ], [ false, false, false ], [ false, false, false
], [ false, false, false ] ]
and I obtained a null Boolean matrix but if I use the following command
A[2][3] := true;
I have the following problem
gap> A;
[ [ false, false, true ], [ false, false, true ], [ false, false, true ], [
false, false, true ] ]
I need just A[2][3] := true not A[i][3].
Would you please help me?
Best regards
Sara
From gordon.royle at uwa.edu.au Wed Mar 2 07:24:40 2016
From: gordon.royle at uwa.edu.au (Gordon Royle)
Date: Wed, 2 Mar 2016 15:24:40 +0800
Subject: [GAP Forum] Boolean matrix
In-Reply-To:
References:
Message-ID:
Each iteration of Add(A,B) simply adds (to A) another reference to the same copy of B, so all four rows of A refer to a single copy of B.
If you change that one copy (using *any* of the references) then every reference to that copy will reflect the change.
You need to actually create four genuine ?deep copies" of B if you want them to be independent.
(I am also not sure whether GAP treats arrays of booleans as bit patterns which is what you would need in order to really save memory)
On 2 Mar 2016, at 2:03 pm, Sara Yaftian > wrote:
Dear GAP Forum
I need a m by n Boolean matrix for saving memory in my works. I know
A:=NullMat(m,n);
is a Null matrix but I need boolean version. I wrote the following code
B:=[];
for i in [1..3] do
Add(B,false);
od;
A:=[B];
for j in [1..3] do
Add(A,B);
od;
this is the output:
gap> A;
[ [ false, false, false ], [ false, false, false ], [ false, false, false
], [ false, false, false ] ]
and I obtained a null Boolean matrix but if I use the following command
A[2][3] := true;
I have the following problem
gap> A;
[ [ false, false, true ], [ false, false, true ], [ false, false, true ], [
false, false, true ] ]
I need just A[2][3] := true not A[i][3].
Would you please help me?
Best regards
Sara
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
Professor Gordon Royle
School of Mathematics and Statistics
University of Western Australia
Gordon.Royle at uwa.edu.au
From alexk at mcs.st-and.ac.uk Tue Mar 8 22:34:19 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Tue, 8 Mar 2016 22:34:19 +0000
Subject: [GAP Forum] Boolean matrix
In-Reply-To:
References:
Message-ID: <36F148EA-875A-4CEB-B54A-FF36473A0FFE@mcs.st-andrews.ac.uk>
Dear Gordon, Sara, dear Forum,
> On 2 Mar 2016, at 07:24, Gordon Royle wrote:
>
> Each iteration of Add(A,B) simply adds (to A) another reference to the same copy of B, so all four rows of A refer to a single copy of B.
>
> If you change that one copy (using *any* of the references) then every reference to that copy will reflect the change.
>
> You need to actually create four genuine ?deep copies" of B if you want them to be independent.
>
> (I am also not sure whether GAP treats arrays of booleans as bit patterns which is what you would need in order to really save memory)
GAP indeed has boolean lists (blists) which are internally represented in
a compact form - see http://www.gap-system.org/Manuals/doc/ref/chap22.html
for further details and some pitfalls to avoid.
Best wishes
Alexander
From l.h.soicher at qmul.ac.uk Wed Mar 9 17:25:58 2016
From: l.h.soicher at qmul.ac.uk (Leonard Soicher)
Date: Wed, 9 Mar 2016 17:25:58 +0000
Subject: [GAP Forum] Important news for users and installers of GRAPE
Message-ID:
Dear GAP Forum,
I am pleased to announce that the new version 4.7 of GRAPE is included
in the recently released GAP 4.8.2. All users and installers of GRAPE
should read this email in its entirety.
The main new feature of GRAPE 4.7 is that the user may run their own
separately installed copy of bliss or nauty or nauty/traces rather
than using the included version of nauty 2.2 included
in GRAPE 4.7. How to do this is described in Chapter 1 of the GRAPE
4.7 manual. Please note that the nauty interface for GRAPE 4.7 has
only been extensively tested with the included version 2.2 of nauty,
and the bliss interface has only been tested with version 0.73 of bliss.
The interface to bliss was originally written by Jerry James (who I
thank), who modified and packaged GRAPE 4.6.1 as a Fedora package
(in Fedora 22, 23 and 24) to use bliss instead of nauty, due to Fedora
licensing rules. Unfortunately, there were some bugs in this initial
interface, which could cause wrong results to be returned. This interface
was fixed for inclusion in GRAPE 4.7 and I am pleased to see that now
there are Fedora package versions of GRAPE 4.7 for Fedora 23 and 24,
but I have not tried them and would appreciate any feedback you have
on those Fedora package versions. However, please note that I can only
guarantee support for official versions of GRAPE obtained either from
http://www.maths.qmul.ac.uk/~leonard/grape/
or as part of the official GAP distribution downloaded from
http://www.gap-system.org
The user should test any installation of GRAPE 4.7 (and its
interface to bliss or nauty or nauty/traces) using the new
GRAPE testfile. In GAP, the command
Test(Filename(DirectoriesPackageLibrary("grape","tst"),"testall.tst"));
should return the value true.
I wish you happy computing with GRAPE 4.7!
Regards,
Leonard
From samuel.lelievre at gmail.com Thu Mar 10 06:01:15 2016
From: samuel.lelievre at gmail.com (=?UTF-8?Q?Samuel_Leli=C3=A8vre?=)
Date: Thu, 10 Mar 2016 07:01:15 +0100
Subject: [GAP Forum] Important news for users and installers of GRAPE
In-Reply-To:
References:
Message-ID:
2016-03-09 18:25 GMT+01:00 Leonard Soicher :
> The interface to bliss was originally written by Jerry James (who I
> thank), who modified and packaged GRAPE 4.6.1 as a Fedora package
> (in Fedora 22, 23 and 24) to use bliss instead of nauty, due to Fedora
> licensing rules.
Note that this might evolve since the authors of Nauty
released version 2.6 under an updated license, see
http://pallini.di.uniroma1.it/
http://users.cecs.anu.edu.au/~bdm/nauty/
and in particular
http://users.cecs.anu.edu.au/~bdm/nauty/COPYRIGHT.txt
Best, Samuel
From z060822400814a at rezozer.net Thu Mar 10 23:33:03 2016
From: z060822400814a at rezozer.net (z060822400814a at rezozer.net)
Date: Fri, 11 Mar 2016 00:33:03 +0100
Subject: [GAP Forum] Important news for users and installers of GRAPE
In-Reply-To:
References:
Message-ID: <56E2042F.6050604@rezozer.net>
Hello Forum:
On 10/03/16 07:01, Samuel Leli?vre wrote:
> 2016-03-09 18:25 GMT+01:00 Leonard Soicher :
>
>> The interface to bliss was originally written by Jerry James (who I
>> thank), who modified and packaged GRAPE 4.6.1 as a Fedora package
>> (in Fedora 22, 23 and 24) to use bliss instead of nauty, due to Fedora
>> licensing rules.
>
> Note that this might evolve since the authors of Nauty
> released version 2.6 under an updated license, see
>
> http://pallini.di.uniroma1.it/
> http://users.cecs.anu.edu.au/~bdm/nauty/
>
> and in particular
>
> http://users.cecs.anu.edu.au/~bdm/nauty/COPYRIGHT.txt
>
> Best, Samuel
Thanks for the notice.
I am on my way to update the nauty package for Debian [1] and to resume
the packaging for GRAPE [2].
Thanks,
Jerome
[1] https://packages.qa.debian.org/n/nauty.html
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=762583
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
From l.h.soicher at qmul.ac.uk Fri Mar 11 10:47:36 2016
From: l.h.soicher at qmul.ac.uk (Leonard Soicher)
Date: Fri, 11 Mar 2016 10:47:36 +0000
Subject: [GAP Forum] Important news for users and installers of GRAPE
In-Reply-To: <56E2042F.6050604@rezozer.net>
References:
,
<56E2042F.6050604@rezozer.net>
Message-ID:
Hello GAP-Forum,
I installed nauty 2.6 (r2), and ran GRAPE 4.7, setting
GRAPE_NAUTY := true;
GRAPE_DREADNAUT_EXE := "mypathto/nauty26r2/dreadnaut";
Initial basic tests indicate that GRAPE 4.7 works with nauty 2.6 (r2),
but I will continue with further checks.
I remark that I have had a problem with bliss crashing on occasion.
Regards,
Leonard
________________________________________
From: forum-bounces at gap-system.org on behalf of z060822400814a at rezozer.net
Sent: 10 March 2016 23:33
To: forum at gap-system.org
Subject: Re: [GAP Forum] Important news for users and installers of GRAPE
Hello Forum:
On 10/03/16 07:01, Samuel Leli?vre wrote:
> 2016-03-09 18:25 GMT+01:00 Leonard Soicher :
>
>> The interface to bliss was originally written by Jerry James (who I
>> thank), who modified and packaged GRAPE 4.6.1 as a Fedora package
>> (in Fedora 22, 23 and 24) to use bliss instead of nauty, due to Fedora
>> licensing rules.
>
> Note that this might evolve since the authors of Nauty
> released version 2.6 under an updated license, see
>
> http://pallini.di.uniroma1.it/
> http://users.cecs.anu.edu.au/~bdm/nauty/
>
> and in particular
>
> http://users.cecs.anu.edu.au/~bdm/nauty/COPYRIGHT.txt
>
> Best, Samuel
Thanks for the notice.
I am on my way to update the nauty package for Debian [1] and to resume
the packaging for GRAPE [2].
Thanks,
Jerome
[1] https://packages.qa.debian.org/n/nauty.html
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=762583
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
_______________________________________________
Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
From axyd0000 at gmail.com Sat Mar 19 06:31:47 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Sat, 19 Mar 2016 12:01:47 +0530
Subject: [GAP Forum] Reduction of elements of FpGroup
Message-ID: <56ECF253.3090303@gmail.com>
Hi GAP forum members,
I am looking at the source code `FpElementNFFunction` (no documentation
for it), in that there is a comment
```
# first try whether the group is ``small''
```
what does "small" means in GAP terms? Is this some standard jargon used
in GAP source code? If so how is this used internally? It will be
helpful if you could explain this used in a little deail.
I believe GAP uses somehow "small" group to refer to groups below
certain "order", if this is the case. To what things it makes things useful?
Thank you
Gaurav
From axyd0000 at gmail.com Sat Mar 19 06:33:13 2016
From: axyd0000 at gmail.com (Gaurav Dhingra)
Date: Sat, 19 Mar 2016 12:03:13 +0530
Subject: [GAP Forum] Reduction of elements of FpGroup
In-Reply-To: <56ECF253.3090303@gmail.com>
References: <56ECF253.3090303@gmail.com>
Message-ID: <56ECF2A9.2010103@gmail.com>
May be here my title of mail is mis-leading. Sorry about that.
On Saturday 19 March 2016 12:01 PM, Gaurav Dhingra wrote:
> Hi GAP forum members,
>
> I am looking at the source code `FpElementNFFunction` (no
> documentation for it), in that there is a comment
> ```
> # first try whether the group is ``small''
> ```
>
> what does "small" means in GAP terms? Is this some standard jargon
> used in GAP source code? If so how is this used internally? It will be
> helpful if you could explain this used in a little deail.
> I believe GAP uses somehow "small" group to refer to groups below
> certain "order", if this is the case. To what things it makes things
> useful?
>
> Thank you
> Gaurav
From sl4 at st-andrews.ac.uk Sat Mar 19 13:20:11 2016
From: sl4 at st-andrews.ac.uk (Stephen Linton)
Date: Sat, 19 Mar 2016 13:20:11 +0000
Subject: [GAP Forum] Reduction of elements of FpGroup
In-Reply-To: <56ECF253.3090303@gmail.com>
References: <56ECF253.3090303@gmail.com>
Message-ID: <5291C739-3221-4470-970B-540286812427@st-andrews.ac.uk>
Dear Gaurav Dhingra,
Firstly, I?m afraid there is no standard meaning of ?small? in GAP. This is simply a comment by the
developer of this routine to explain what the next few lines are doing.
In fact we can see from the next lines that the test is whether the group can be seen to have order less than 50000. That is whether a faithful homomorphism is known, or can be found (FPFaithHom) and if so whether the image has order < 50000.
This information is used to choose between two different ways of reducing the element to normal form. For ?small? groups
the work is done in Factorisation which produces short words and is quick for small groups but can be very slow for larger ones. For larger groups a more sophisticated method is used, which may produce longer normal words, and requires quite a lot of setup but can be much faster for very large groups.
Steve
> On 19 Mar 2016, at 06:31, Gaurav Dhingra wrote:
>
> Hi GAP forum members,
>
> I am looking at the source code `FpElementNFFunction` (no documentation for it), in that there is a comment
> ```
> # first try whether the group is ``small''
> ```
>
> what does "small" means in GAP terms? Is this some standard jargon used in GAP source code? If so how is this used internally? It will be helpful if you could explain this used in a little deail.
> I believe GAP uses somehow "small" group to refer to groups below certain "order", if this is the case. To what things it makes things useful?
>
> Thank you
> Gaurav
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From graham.ellis at nuigalway.ie Mon Mar 21 09:53:01 2016
From: graham.ellis at nuigalway.ie (Ellis, Grahamj)
Date: Mon, 21 Mar 2016 09:53:01 +0000
Subject: [GAP Forum] lectureship at Galway
In-Reply-To:
References: <561E0F8F.3080502@gmail.com>
,
<56C33D7B.50403@gmail.com>,
,
,
,
,
Message-ID:
A permanent lectureship in mathematics at NUI Galway was advertized last Friday.
See http://www.nuigalway.ie/media/humanresources/publicdocuments/Lecturer-BTB_Maths.docx .
The closing date is 28 April 2016.
All the best,
Graham
School of Mathematics, Statistics & Applied Mathematics
National University of Ireland, Galway
University Road,
Galway
Ireland
http://hamilton.nuigalway.ie
tel: 091 493011
From alexk at mcs.st-and.ac.uk Thu Mar 24 15:37:40 2016
From: alexk at mcs.st-and.ac.uk (Alexander Konovalov)
Date: Thu, 24 Mar 2016 15:37:40 +0000
Subject: [GAP Forum] GAP 4.8.3 release announcement
Message-ID:
Dear GAP Forum,
This is to announce the release of GAP 4.8.3, which could be downloaded from
http://www.gap-system.org/Releases/
An overview of the changes introduced in GAP 4.8.3 is provided below. A more
detailed version with hyperlinks to documentation is available here:
http://www.gap-system.org/Manuals/doc/changes/chap2.htm
New features:
* New function TestPackage to run standard tests (if available) for a single
package in the current GAP session. This function is also callable via
make testpackage PKGNAME=pkgname
to run package tests in the same settings that are used for testing GAP
releases.
Improved and extended functionality:
* TestDirectory now prints a special status message to indicate the outcome of
the test (this is convenient for automated testing). If necessary, this message
may be suppressed by using the option suppressStatusMessage
* Improved output of tracing methods (which may be invoked, for example, with
TraceAllMethods) by displaying filename and line number in some more cases.
Changed functionality:
* Fixed some inconsistencies in the usage of IsGeneratorsOfSemigroup.
Fixed bugs that could lead to incorrect results:
* Fallback methods for conjugacy classes, that were intended only for finite
groups, now use IsFinite filter to prevent them being called for infinite
groups. [Reported by Gabor Horvath]
Fixed bugs that could lead to break loops:
* Calculating stabiliser for the alternating group caused a break loop in
the case when it defers to the corresponding symmetric group.
* It was not possible to use DotFileLatticeSubgroups for a trivial group.
[Reported by Sergio Siccha]
* A break loop while computing AutomorphismGroup for TransitiveGroup(12,269).
[Reported by Ignat Soroko]
* A break loop while computing conjugacy classes of PSL(6,4).
[Reported by Martin Macaj]
Other fixed bugs:
* Fix for using Firefox as a default help viewer with SetHelpViewer.
[Reported by Tom McDonough]
In addition, GAP 4.8.3 distribution includes updates for 29 packages:
====================================================
Package name | Version | Date
----------------------------------------------------
ACE | 5.2 | 11/03/2016
ANUPQ | 3.1.4 | 08/03/2016
AutoDoc | 2016.03.08 | 08/03/2016
CRISP | 1.4.3 | 29/02/2016
cvec | 2.5.5 | 08/03/2016
Digraphs | 0.5 | 03/03/2016
FGA | 1.3.1 | 28/02/2016
fr | 2.3.3 | 27/02/2016
GBNP | 1.0.3 | 08/03/2016
genss | 1.6.4 | 08/03/2016
GUAVA | 3.13 | 31/01/2016
HeLP | 3.0 | 03/03/2016
IO | 4.4.6 | 08/03/2016
matgrp | 0.4 | 25/02/2015
NormalizInterface | 0.9.7 | 10/03/2016
nq | 2.5.3 | 08/03/2016
orb | 4.7.6 | 08/03/2016
Polenta | 1.3.6 | 08/03/2016
profiling | 0.5.1 | 24/02/2016
qaos | 1.2 | 25/02/2016
QPA | 1.24 | 24/02/2016
RCWA | 4.3.1 | 09/03/2016
recog | 1.2.5 | 08/03/2016
recogbase | 1.2.5 | 08/03/2016
ResClasses | 4.4.2 | 09/03/2016
Semigroups | 2.7.4 | 02/03/2016
Utils | 0.39 | 04/03/2016
XGAP | 4.24 | 28/02/2016
XMod | 2.56 | 08/03/2016
====================================================
We encourage all users to upgrade to GAP 4.8.3. If you need any help or
would like to report any problems, please do not hesitate to contact us
at support at gap-system.org or submit new issues on GitHub:
https://github.com/gap-system/gap/issues
Wishing you fun and success using GAP,
The GAP Group
From z060822400814a at rezozer.net Sat Mar 26 16:08:53 2016
From: z060822400814a at rezozer.net (z060822400814a at rezozer.net)
Date: Sat, 26 Mar 2016 17:08:53 +0100
Subject: [GAP Forum] Important news for users and installers of GRAPE:
[DEBIAN]
In-Reply-To:
References:
<56E2042F.6050604@rezozer.net>
Message-ID: <56F6B415.8020106@rezozer.net>
Hello Forum:
GRAPE is now available as Debian package (DFSG-free) [1].
Note that the nauty Debian package has migrated from non-free to main (DFSG-free) [2]
as nauty is now distributed under the Apache 2.0 license.
Thanks,
Jerome
[1] https://packages.qa.debian.org/g/gap-grape.html
[2] https://packages.qa.debian.org/n/nauty.html
On 11/03/16 11:47, Leonard Soicher wrote:
> Hello GAP-Forum,
>
> I installed nauty 2.6 (r2), and ran GRAPE 4.7, setting
>
> GRAPE_NAUTY := true; GRAPE_DREADNAUT_EXE :=
> "mypathto/nauty26r2/dreadnaut";
>
> Initial basic tests indicate that GRAPE 4.7 works with nauty 2.6
> (r2), but I will continue with further checks.
>
> I remark that I have had a problem with bliss crashing on occasion.
>
> Regards, Leonard
>
> ________________________________________ From:
> forum-bounces at gap-system.org on behalf
> of z060822400814a at rezozer.net Sent: 10
> March 2016 23:33 To: forum at gap-system.org Subject: Re: [GAP Forum]
> Important news for users and installers of GRAPE
>
> Hello Forum:
>
> On 10/03/16 07:01, Samuel Leli?vre wrote:
>> 2016-03-09 18:25 GMT+01:00 Leonard Soicher
>> :
>>
>>> The interface to bliss was originally written by Jerry James (who
>>> I thank), who modified and packaged GRAPE 4.6.1 as a Fedora
>>> package (in Fedora 22, 23 and 24) to use bliss instead of nauty,
>>> due to Fedora licensing rules.
>>
>> Note that this might evolve since the authors of Nauty released
>> version 2.6 under an updated license, see
>>
>> http://pallini.di.uniroma1.it/
>> http://users.cecs.anu.edu.au/~bdm/nauty/
>>
>> and in particular
>>
>> http://users.cecs.anu.edu.au/~bdm/nauty/COPYRIGHT.txt
>>
>> Best, Samuel
>
> Thanks for the notice.
>
> I am on my way to update the nauty package for Debian [1] and to
> resume the packaging for GRAPE [2].
>
> Thanks, Jerome
>
> [1] https://packages.qa.debian.org/n/nauty.html [2]
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=762583
>
>
>>
>> _______________________________________________ Forum mailing list
>> Forum at mail.gap-system.org
>> http://mail.gap-system.org/mailman/listinfo/forum
>>
>
> _______________________________________________ Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
From s.dikson2016 at gmail.com Mon Apr 11 08:19:55 2016
From: s.dikson2016 at gmail.com (Sara Dikson)
Date: Mon, 11 Apr 2016 11:49:55 +0430
Subject: [GAP Forum] Used memory for a process
Message-ID:
Dear Forum,
I am using a super computer for some processes. But suddenly, the GAP
screen will be closed when my program is running.
How can I prevent this problem?
I would like to use all memory and run more than one program
simultaneously.
How can I do that?
Best regards,
Sara.
From dmitrii.pasechnik at cs.ox.ac.uk Mon Apr 11 09:08:17 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dima Pasechnik)
Date: Mon, 11 Apr 2016 09:08:17 +0100
Subject: [GAP Forum] Used memory for a process
In-Reply-To:
References:
Message-ID: <20160411080817.GA20376@dimpase.cs.ox.ac.uk>
Dear Sara,
On Mon, Apr 11, 2016 at 11:49:55AM +0430, Sara Dikson wrote:
> I am using a super computer for some processes. But suddenly, the GAP
> screen will be closed when my program is running.
> How can I prevent this problem?
it depends a lot on how your supercomputer is set up.
Often you can only run jobs which are "big" - either memory-wise or CPU-time wise
only as a batch job, and not interactively.
It could well be that this is exactly what causes your issue.
One way or another, typically, if you need to run a task on a remote machine
(super or not) you run it using a program called screen.
https://www.gnu.org/software/screen/manual/screen.html
> I would like to use all memory and run more than one program
> simultaneously.
> How can I do that?
how GAP controls the amount of memory it can use, is described in the GAP
manual. Again, it is not clear how your GAP in installed, whether the amount of
RAM it can use is controlled by the supercomputer scheduler, etc...
More details would be needed - perhaps you should talk to your supercomputer
admins, too.
If you use screen, then you can have many sessions of it running, with a GAP session in each of them.
HTH,
Dima
From f.k.moftakhar at gmail.com Sat Apr 16 12:33:19 2016
From: f.k.moftakhar at gmail.com (fatemeh moftakhar)
Date: Sat, 16 Apr 2016 16:03:19 +0430
Subject: [GAP Forum] Source code of GAP
Message-ID:
Dear Forum
The command "Print(ff)" in GAP gives the code of the "ff" written in GAP.
See for example the following command in GAP:
gap> Print(Combinations);
function ( arg )
local combs, mset;
if Length( arg ) = 1 then
mset := ShallowCopy( arg[1] );
Sort( mset );
combs := CombinationsA( mset, 1, Length( mset ), [ ], 1 );
elif Length( arg ) = 2 then
mset := ShallowCopy( arg[1] );
Sort( mset );
combs := CombinationsK( mset, 1, Length( mset ), arg[2], [ ], 1 );
else
Error( "usage: Combinations( [, ] )" );
fi;
return combs;
end
If I run the command "Print(CharacterTable)", then we can see the following
GAP message:
gap> Print(CharacterTable);
Is it possible to find the GAP code for CharacterTable?
If no, is it possible to find the source of the program for calculating
with primitive roots of unity in GAP?
finally where is the library of primitive roots of unity? For example I
need to source program of GAP for computing E(8)-E(8)^3?
Best regards
Fatemeh Moftakhar
--
Regards;
Miss Fatemeh Moftakhar
PhD Candidate,
Department of Pure Mathematics,
Faculty of Mathematical Sciences,
University of Kashan, Kashan, Iran
From caj21 at st-andrews.ac.uk Sat Apr 16 13:59:05 2016
From: caj21 at st-andrews.ac.uk (Christopher Jefferson)
Date: Sat, 16 Apr 2016 12:59:05 +0000
Subject: [GAP Forum] Source code of GAP
In-Reply-To:
References:
Message-ID:
For operations like CharacterTable, there are several implementations in GAP. To find out what is actually called, you can (often) use 'ApplicableMethod', which accepts a function and it's arguments (as a list)
For example, Print(ApplicableMethod(CharacterTable, [AlternatingGroup(5)])) shows the function for finding this character table.
Unfortunately, if we try the same for primitive root, we get:
gap> Print(ApplicableMethod(PrimitiveRoot, [GF(3^5)]));
function ( object )
<>
end
This tells us this code is not written in GAP, but instead in C.
On 16/04/2016, 12:33, "forum-bounces at gap-system.org on behalf of fatemeh moftakhar" wrote:
>Dear Forum
>
>The command "Print(ff)" in GAP gives the code of the "ff" written in GAP.
>See for example the following command in GAP:
>gap> Print(Combinations);
>function ( arg )
> local combs, mset;
> if Length( arg ) = 1 then
> mset := ShallowCopy( arg[1] );
> Sort( mset );
> combs := CombinationsA( mset, 1, Length( mset ), [ ], 1 );
> elif Length( arg ) = 2 then
> mset := ShallowCopy( arg[1] );
> Sort( mset );
> combs := CombinationsK( mset, 1, Length( mset ), arg[2], [ ], 1 );
> else
> Error( "usage: Combinations( [, ] )" );
> fi;
> return combs;
>end
>
>If I run the command "Print(CharacterTable)", then we can see the following
>GAP message:
>
>gap> Print(CharacterTable);
>
>
>Is it possible to find the GAP code for CharacterTable?
>
>If no, is it possible to find the source of the program for calculating
>with primitive roots of unity in GAP?
>
>finally where is the library of primitive roots of unity? For example I
>need to source program of GAP for computing E(8)-E(8)^3?
>
>Best regards
>Fatemeh Moftakhar
>
>--
>Regards;
>Miss Fatemeh Moftakhar
>PhD Candidate,
>Department of Pure Mathematics,
>Faculty of Mathematical Sciences,
>University of Kashan, Kashan, Iran
>_______________________________________________
>Forum mailing list
>Forum at mail.gap-system.org
>http://mail.gap-system.org/mailman/listinfo/forum
From sam at Math.RWTH-Aachen.De Sun Apr 17 13:34:28 2016
From: sam at Math.RWTH-Aachen.De (Thomas Breuer)
Date: Sun, 17 Apr 2016 14:34:28 +0200
Subject: [GAP Forum] Source code of GAP
In-Reply-To:
References:
Message-ID: <20160417123428.GB9297@gemma.math.rwth-aachen.de>
Dear GAP Forum,
probably the question is about the GAP functions that compute
the irreducible characters of a given group,
not about the function 'CharacterTable'.
If yes then one should look for the methods for the function 'Irr',
for example using 'ApplicableMethod'.
Concerning the question about calculations with primitive roots
of unity, I would suggest to look at the chapters ``Cyclotomics''
and ``Abelian Number Fields'' of the GAP Reference Manual.
Also the paper cited as [Bre97] in this manual might be of interest.
All the best,
Thomas
On Sat, Apr 16, 2016 at 04:03:19PM +0430, fatemeh moftakhar wrote:
> Dear Forum
>
> The command "Print(ff)" in GAP gives the code of the "ff" written in GAP.
> See for example the following command in GAP:
> gap> Print(Combinations);
> function ( arg )
> local combs, mset;
> if Length( arg ) = 1 then
> mset := ShallowCopy( arg[1] );
> Sort( mset );
> combs := CombinationsA( mset, 1, Length( mset ), [ ], 1 );
> elif Length( arg ) = 2 then
> mset := ShallowCopy( arg[1] );
> Sort( mset );
> combs := CombinationsK( mset, 1, Length( mset ), arg[2], [ ], 1 );
> else
> Error( "usage: Combinations( [, ] )" );
> fi;
> return combs;
> end
>
> If I run the command "Print(CharacterTable)", then we can see the following
> GAP message:
>
> gap> Print(CharacterTable);
>
>
> Is it possible to find the GAP code for CharacterTable?
>
> If no, is it possible to find the source of the program for calculating
> with primitive roots of unity in GAP?
>
> finally where is the library of primitive roots of unity? For example I
> need to source program of GAP for computing E(8)-E(8)^3?
>
> Best regards
> Fatemeh Moftakhar
From f.k.moftakhar at gmail.com Sun Apr 17 19:33:45 2016
From: f.k.moftakhar at gmail.com (fatemeh moftakhar)
Date: Sun, 17 Apr 2016 23:03:45 +0430
Subject: [GAP Forum] Source code of GAP
In-Reply-To: <20160417123428.GB9297@gemma.math.rwth-aachen.de>
References:
<20160417123428.GB9297@gemma.math.rwth-aachen.de>
Message-ID:
Dear Professors Stefan Kohl, Chiristopher Jefferson and Thomas Breuer
Thank you very much for your useful comments.
Have a nice week ahead.
Bset regards
Fatemeh Moftakhar
On Sun, Apr 17, 2016 at 5:04 PM, Thomas Breuer
wrote:
> Dear GAP Forum,
>
> probably the question is about the GAP functions that compute
> the irreducible characters of a given group,
> not about the function 'CharacterTable'.
>
> If yes then one should look for the methods for the function 'Irr',
> for example using 'ApplicableMethod'.
>
> Concerning the question about calculations with primitive roots
> of unity, I would suggest to look at the chapters ``Cyclotomics''
> and ``Abelian Number Fields'' of the GAP Reference Manual.
> Also the paper cited as [Bre97] in this manual might be of interest.
>
> All the best,
> Thomas
>
>
> On Sat, Apr 16, 2016 at 04:03:19PM +0430, fatemeh moftakhar wrote:
> > Dear Forum
> >
> > The command "Print(ff)" in GAP gives the code of the "ff" written in GAP.
> > See for example the following command in GAP:
> > gap> Print(Combinations);
> > function ( arg )
> > local combs, mset;
> > if Length( arg ) = 1 then
> > mset := ShallowCopy( arg[1] );
> > Sort( mset );
> > combs := CombinationsA( mset, 1, Length( mset ), [ ], 1 );
> > elif Length( arg ) = 2 then
> > mset := ShallowCopy( arg[1] );
> > Sort( mset );
> > combs := CombinationsK( mset, 1, Length( mset ), arg[2], [ ], 1
> );
> > else
> > Error( "usage: Combinations( [, ] )" );
> > fi;
> > return combs;
> > end
> >
> > If I run the command "Print(CharacterTable)", then we can see the
> following
> > GAP message:
> >
> > gap> Print(CharacterTable);
> >
> >
> > Is it possible to find the GAP code for CharacterTable?
> >
> > If no, is it possible to find the source of the program for calculating
> > with primitive roots of unity in GAP?
> >
> > finally where is the library of primitive roots of unity? For example I
> > need to source program of GAP for computing E(8)-E(8)^3?
> >
> > Best regards
> > Fatemeh Moftakhar
>
>
--
Regards;
Miss Fatemeh Moftakhar
PhD Candidate,
Department of Pure Mathematics,
Faculty of Mathematical Sciences,
University of Kashan, Kashan, Iran
From s.dikson2016 at gmail.com Tue Apr 19 07:56:19 2016
From: s.dikson2016 at gmail.com (Sara Dikson)
Date: Tue, 19 Apr 2016 11:26:19 +0430
Subject: [GAP Forum] "SimpleGroup" command
Message-ID:
Dear Forum
I used the "SimpleGroup("J4");" command for the Janko group.
But Gap can't recognize it. Also I used "AtlasGroup("J4");" but it return
"fail". I try it for "J3" but it return "fail".?
errorg.png
?
How can I access to all simple groups?
I send the error as an attachment.
Best regards
Sara
From dmitrii.pasechnik at cs.ox.ac.uk Tue Apr 19 09:35:47 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dima Pasechnik)
Date: Tue, 19 Apr 2016 09:35:47 +0100
Subject: [GAP Forum] "SimpleGroup" command
In-Reply-To:
References:
Message-ID: <20160419083547.GA25303@dimpase.cs.ox.ac.uk>
Dear Sarah,
On Tue, Apr 19, 2016 at 11:26:19AM +0430, Sara Dikson wrote:
> Dear Forum
> I used the "SimpleGroup("J4");" command for the Janko group.
> But Gap can't recognize it. Also I used "AtlasGroup("J4");" but it return
> "fail". I try it for "J3" but it return "fail".?
AtlasGroup("J3") and AtlasGroup("J4") should work, provided you have the necessary pre-requisits
on. As far as I know it does not quite work on Windows, as it won't be able to get the data from the net.
(Or it used to be the case in the past).
Although you can download the data it needs manually.
> errorg.png
>
you did not set the permissions on this link to be public, I cannot open it.
HTH,
Dmitrii
From arashrafi at kashanu.ac.ir Tue Apr 19 09:43:44 2016
From: arashrafi at kashanu.ac.ir (arashrafi at kashanu.ac.ir)
Date: Tue, 19 Apr 2016 13:13:44 +0430 (IRDT)
Subject: [GAP Forum] "SimpleGroup" command
In-Reply-To: <4646042.13146.1461054974790.JavaMail.root@mail.kashanu.ac.ir>
Message-ID: <24089212.13148.1461055424897.JavaMail.root@mail.kashanu.ac.ir>
Dear Sara,
The character table of "J4" can be computed by the following command:
gap> CharacterTable("j4");
For sporadic groups, it is possible to work with character tables (and no with groups other than Mathieu groups). But, a permutation or
matrix representation for some sporadic groups are recorded in
ATLAS of Finite Group Representations - Version 3 (http://brauer.maths.qmul.ac.uk/Atlas/v3/spor/). You can copy a generator set for "j4" from ATLAS and then paste into GAP. But you need a good computer.
I hope this help you.
Regards, Alireza
----- Original Message -----
From: "Sara Dikson"
To: forum at gap-system.org
Sent: Monday, April 18, 2016 11:56:19 PM
Subject: [GAP Forum] "SimpleGroup" command
Dear Forum
I used the "SimpleGroup("J4");" command for the Janko group.
But Gap can't recognize it. Also I used "AtlasGroup("J4");" but it
return "fail". I try it for "J3" but it return "fail".?
errorg.png
? How can I access to all simple groups?
I send the error as an attachment.
Best regards
Sara
_______________________________________________ Forum mailing list
Forum at mail.gap-system.org
http://mail.gap-system.org/mailman/listinfo/forum
From alexander.konovalov at st-andrews.ac.uk Tue Apr 19 10:12:12 2016
From: alexander.konovalov at st-andrews.ac.uk (Alexander Konovalov)
Date: Tue, 19 Apr 2016 09:12:12 +0000
Subject: [GAP Forum] "SimpleGroup" command
In-Reply-To: <20160419083547.GA25303@dimpase.cs.ox.ac.uk>
References:
<20160419083547.GA25303@dimpase.cs.ox.ac.uk>
Message-ID:
Dear Sara, Dima,
No, this should work on Windows. It uses IO package to download data from the remote
host, and GAP distribution for Windows includes IO binaries. Sara, which operating
system do you actually have?
This is where things may go wrong for AtlasRep:
1) IO package not compiled. Then AtlasRep may try to fallback to using wget for
downloads, but if that is missing too, it will fail.
2) No internet connection, or some restrictive firewall settings.
3) No write permission in the directory where AtlasRep tries to write data.
It will be useful to see the error message (and it is better to copy and paste
the text into email instead of providing a screenshot) for the further advice.
Hope this helps
Alexander
> On 19 Apr 2016, at 09:35, Dima Pasechnik wrote:
>
> Dear Sarah,
>
> On Tue, Apr 19, 2016 at 11:26:19AM +0430, Sara Dikson wrote:
>> Dear Forum
>> I used the "SimpleGroup("J4");" command for the Janko group.
>> But Gap can't recognize it. Also I used "AtlasGroup("J4");" but it return
>> "fail". I try it for "J3" but it return "fail".?
>
> AtlasGroup("J3") and AtlasGroup("J4") should work, provided you have the necessary pre-requisits
> on. As far as I know it does not quite work on Windows, as it won't be able to get the data from the net.
> (Or it used to be the case in the past).
> Although you can download the data it needs manually.
>
>
>> errorg.png
>>
>
> you did not set the permissions on this link to be public, I cannot open it.
>
> HTH,
> Dmitrii
From z060822400814a at rezozer.net Tue Apr 19 12:53:43 2016
From: z060822400814a at rezozer.net (z060822400814a at rezozer.net)
Date: Tue, 19 Apr 2016 12:53:43 +0100
Subject: [GAP Forum] gapdoc: BibTeX: url
Message-ID: <57161C47.8090909@rezozer.net>
Hello Forum:
in a bib data file with which I am dealing, there is the entry
@misc{Br,
author = {A.~E. Brouwer},
title = {Bounds on the minimum distance of linear codes},
howpublished = {\url{http://www.win.tue.nl/~aeb/voorlincod.html}},
year = {1997?2006},
}
When this bib data file is transformed to an XML file through the following commands
bibdata := ParseBibFiles("doc/dum.bib");;
WriteBibXMLextFile("doc/dum_bib.xml",bibdata), I get:
A. E.Brouwer
Bounds on the minimum distance of linear codes
\url{http://www.win.tue.nl/~aeb/voorlincod.html}
1997?2006
Is it possible to get a more appropriate URL output in the XML output ?
Thanks in advance,
Jerome
From dmitrii.pasechnik at cs.ox.ac.uk Tue Apr 19 13:25:34 2016
From: dmitrii.pasechnik at cs.ox.ac.uk (Dima Pasechnik)
Date: Tue, 19 Apr 2016 13:25:34 +0100
Subject: [GAP Forum] gapdoc: BibTeX: url
In-Reply-To: <57161C47.8090909@rezozer.net>
References: <57161C47.8090909@rezozer.net>
Message-ID: <20160419122534.GA30120@dimpase.cs.ox.ac.uk>
On Tue, Apr 19, 2016 at 12:53:43PM +0100, z060822400814a at rezozer.net wrote:
> Hello Forum:
>
> in a bib data file with which I am dealing, there is the entry
>
> @misc{Br,
> author = {A.~E. Brouwer},
> title = {Bounds on the minimum distance of linear codes},
> howpublished = {\url{http://www.win.tue.nl/~aeb/voorlincod.html}},
> year = {1997?2006},
> }
for what it's worth, this link is obsolete. These tables now live in http://www.codetables.de/
Just in case,
Dima
From z060822400814a at rezozer.net Tue Apr 19 13:42:29 2016
From: z060822400814a at rezozer.net (z060822400814a at rezozer.net)
Date: Tue, 19 Apr 2016 13:42:29 +0100
Subject: [GAP Forum] gapdoc: BibTeX: url
In-Reply-To: <20160419122534.GA30120@dimpase.cs.ox.ac.uk>
References: <57161C47.8090909@rezozer.net>
<20160419122534.GA30120@dimpase.cs.ox.ac.uk>
Message-ID: <571627B5.80703@rezozer.net>
Hi Dima, thanks for remark.
On 19/04/16 13:25, Dima Pasechnik wrote:
> On Tue, Apr 19, 2016 at 12:53:43PM +0100, z060822400814a at rezozer.net wrote:
>> Hello Forum:
>>
>> in a bib data file with which I am dealing, there is the entry
>>
>> @misc{Br,
>> author = {A.~E. Brouwer},
>> title = {Bounds on the minimum distance of linear codes},
>> howpublished = {\url{http://www.win.tue.nl/~aeb/voorlincod.html}},
>> year = {1997?2006},
>> }
> for what it's worth, this link is obsolete. These tables now live in http://www.codetables.de/
>
Indeed, as some part of the full bib data file:
I am not maintaining the GAP package itself, but its Debian package:
once my Debian is ready, I will submit patch to the upstream maintainer
of the GAP package. Whatever, for now, I want to fix some documentation
issue, what is my job; revisiting and refreshing is rather under the authority
of the upstream maintainer.
Best wishes,
Jerome
> Just in case,
> Dima
>
From rafaelv at uaeh.edu.mx Tue Apr 19 22:06:57 2016
From: rafaelv at uaeh.edu.mx (Rafael Villarroel)
Date: Tue, 19 Apr 2016 16:06:57 -0500
Subject: [GAP Forum] procedure to change a permutation, not returning it
Message-ID: <87a8kp1f66.fsf@uaeh.edu.mx>
Hello GAP forum,
Is it possible to define a function that returns, say, an integer, but
changes a permutation given as argument, as a side effect.
Something like this:
testperm := function(s)
local i;
i := 1;
s := s^-1;
Print(s,"\n");
return i;
end;
but that when running it like this...
gap> a:=(1,2,3);
(1,2,3)
gap> testperm(a);
(1,3,2)
1
gap> a;
(1,2,3)
...actually changes the permutation a.
Thanks in advance,
Rafael
From caj21 at st-andrews.ac.uk Tue Apr 19 22:14:28 2016
From: caj21 at st-andrews.ac.uk (Christopher Jefferson)
Date: Tue, 19 Apr 2016 21:14:28 +0000
Subject: [GAP Forum] procedure to change a permutation, not returning it
In-Reply-To: <87a8kp1f66.fsf@uaeh.edu.mx>
References: <87a8kp1f66.fsf@uaeh.edu.mx>
Message-ID:
The short answer is no I'm afraid.
The slightly longer answer is while you can't do this, you can do something similar if you pass in a list containing a permutation, or a record with a permutation member, and change that. For example:
testperm := function(s)
local i;
i := 1;
s[1] := s[1]^-1;
Print(s,"\n");
return i;
end;
gap> a:=[(1,2,3)];
[ (1,2,3) ]
gap> testperm(a);
[ (1,3,2) ]
1
gap> a;
[ (1,3,2) ]
You might think, why can I change lists? The rule is you can change members of a list (or members of a record), but not the list itself. For example, if in our function we wrote ' s := [(3,2,1)] ', we would find that didn't change a, because now we are changing s, not a member of s.
Chris
On 19/04/2016, 22:06, "forum-bounces at gap-system.org on behalf of Rafael Villarroel" wrote:
>
>Hello GAP forum,
>
>Is it possible to define a function that returns, say, an integer, but
>changes a permutation given as argument, as a side effect.
>
>Something like this:
>
>testperm := function(s)
> local i;
> i := 1;
> s := s^-1;
> Print(s,"\n");
> return i;
>end;
>
>but that when running it like this...
>
>gap> a:=(1,2,3);
>(1,2,3)
>gap> testperm(a);
>(1,3,2)
>1
>gap> a;
>(1,2,3)
>
>...actually changes the permutation a.
>
>Thanks in advance,
>Rafael
>
>
>_______________________________________________
>Forum mailing list
>Forum at mail.gap-system.org
>http://mail.gap-system.org/mailman/listinfo/forum
From wclark at mail.usf.edu Thu Apr 28 20:01:13 2016
From: wclark at mail.usf.edu (W. Edwin Clark)
Date: Thu, 28 Apr 2016 15:01:13 -0400
Subject: [GAP Forum] Checking equality of elements of words in a finitely
presented group
Message-ID:
I am trying to use GAP to establish equality of two words in a finitely
presented group and am having problems.
First here is a successful test case:
f:=FreeGroup(5);;
rel:=[(f.(5)*f.(1))^5];;
g:=f/rel;;
u:=GeneratorsOfGroup(g);;
(u[5]*u[1])^5 = Identity(g); #testing this identity which is actually a
given relation works successfully
true
But if I add some more relators to rel, I cannot even get
equality to the identity of the first relator. Here's what I tried:
f:=FreeGroup(5);;
rel:=[(f.(5)*f.(1))^5];;
for i in [1..4] do
Add(rel,(f.(i)*f.(i+1))*(f.(5)*f.(1))^(-1));
od;
rel;;
g:=f/rel;;
u:=GeneratorsOfGroup(g);
(u[5]*u[1])^5 = Identity(g); #I gave up waiting for an answer
Why is this so difficult?
What I really want in this group is to show that
u[1]^5*u[2]*u[4]*u[1]*u[3]*u[5] = Identity(g)
Any help would be appreciated.
--Edwin Clark
From D.F.Holt at warwick.ac.uk Fri Apr 29 14:01:19 2016
From: D.F.Holt at warwick.ac.uk (Derek Holt)
Date: Fri, 29 Apr 2016 14:01:19 +0100
Subject: [GAP Forum] Checking equality of elements of words in a
finitely presented group
In-Reply-To:
References:
Message-ID: <20160429130119.GB5543@warwick.ac.uk>
Dear Edwin, dear GAP Forum
You can attempt to solve problems like this using the kbmag package (which
needs to be compiled). I would guess that it is also possible to do so
using the built-in GAP Knuth-Bendix rewriting system functionality, but
I will leave someone else to help with that, since I am not so familiar
with it.
In this example, we are fortunate and, although the group is infinite, we get
a finite confluent rewriting system (with 1734 rewrite rules), which we can
use to solve the word problem.
In most examples of infinite groups defined by a finite presentation, you
do not get a finite confluent rewriting system (although you still may
be able to find an automatic structure), but you can still use the rewrite
rules to attempt to prove that eleemnts are equal to the identity. In this
situation, you cannot in general prove that an element is not equal to the
identity, but you can verify that it is.
Here are the commands need for this calcualtion using kbmag.
LoadPackage("kbmag");
f:=FreeGroup(5);;
rel:=[(f.(5)*f.(1))^5];;
for i in [1..4] do
Add(rel,(f.(i)*f.(i+1))*(f.(5)*f.(1))^(-1));
od;
g:=f/rel;;
R:=KBMAGRewritingSystem(g);;
MakeConfluent(R);
#true
F:=FreeStructureOfRewritingSystem(R);;
u := GeneratorsOfGroup(F);;
ReducedWord(R, (u[5]*u[1])^5);
#
ReducedWord(R, u[1]^5*u[2]*u[4]*u[1]*u[3]*u[5]);
#
Good luck!
Derek Holt.
On Thu, Apr 28, 2016 at 03:01:13PM -0400, W. Edwin Clark wrote:
> I am trying to use GAP to establish equality of two words in a finitely
> presented group and am having problems.
>
> First here is a successful test case:
>
> f:=FreeGroup(5);;
> rel:=[(f.(5)*f.(1))^5];;
> g:=f/rel;;
> u:=GeneratorsOfGroup(g);;
> (u[5]*u[1])^5 = Identity(g); #testing this identity which is actually a
> given relation works successfully
>
> true
>
> But if I add some more relators to rel, I cannot even get
> equality to the identity of the first relator. Here's what I tried:
>
> f:=FreeGroup(5);;
> rel:=[(f.(5)*f.(1))^5];;
> for i in [1..4] do
> Add(rel,(f.(i)*f.(i+1))*(f.(5)*f.(1))^(-1));
> od;
> rel;;
> g:=f/rel;;
> u:=GeneratorsOfGroup(g);
>
> (u[5]*u[1])^5 = Identity(g); #I gave up waiting for an answer
>
> Why is this so difficult?
>
> What I really want in this group is to show that
>
> u[1]^5*u[2]*u[4]*u[1]*u[3]*u[5] = Identity(g)
>
> Any help would be appreciated.
>
> --Edwin Clark
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From jdm3 at st-andrews.ac.uk Fri Apr 29 09:36:01 2016
From: jdm3 at st-andrews.ac.uk (James Mitchell)
Date: Fri, 29 Apr 2016 08:36:01 +0000
Subject: [GAP Forum] Checking equality of elements of words in a
finitely presented group
In-Reply-To: <2db1c285781d4b0f875aac4da0f4b261@AM3PR06MB1362.eurprd06.prod.outlook.com>
References: <2db1c285781d4b0f875aac4da0f4b261@AM3PR06MB1362.eurprd06.prod.outlook.com>
Message-ID:
Dear Edwin,
Probably someone else will reply with a more elaborate answer, but you
might want to consult:
https://en.wikipedia.org/wiki/Word_problem_for_groups#Unsolvability_of_the_uniform_word_problem
A very short answer is that the word problem for finitely presented groups
is unsolvable, i.e. it is known that there is no single algorithm that can
for every finitely presented group say whether two words represent the same
element.
Best wishes,
James
On Thu, 28 Apr 2016 at 20:03 W. Edwin Clark wrote:
> I am trying to use GAP to establish equality of two words in a finitely
> presented group and am having problems.
>
> First here is a successful test case:
>
> f:=FreeGroup(5);;
> rel:=[(f.(5)*f.(1))^5];;
> g:=f/rel;;
> u:=GeneratorsOfGroup(g);;
> (u[5]*u[1])^5 = Identity(g); #testing this identity which is actually a
> given relation works successfully
>
> true
>
> But if I add some more relators to rel, I cannot even get
> equality to the identity of the first relator. Here's what I tried:
>
> f:=FreeGroup(5);;
> rel:=[(f.(5)*f.(1))^5];;
> for i in [1..4] do
> Add(rel,(f.(i)*f.(i+1))*(f.(5)*f.(1))^(-1));
> od;
> rel;;
> g:=f/rel;;
> u:=GeneratorsOfGroup(g);
>
> (u[5]*u[1])^5 = Identity(g); #I gave up waiting for an answer
>
> Why is this so difficult?
>
> What I really want in this group is to show that
>
> u[1]^5*u[2]*u[4]*u[1]*u[3]*u[5] = Identity(g)
>
> Any help would be appreciated.
>
> --Edwin Clark
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
>
From z060822400814a at rezozer.net Fri Apr 29 20:04:00 2016
From: z060822400814a at rezozer.net (z060822400814a at rezozer.net)
Date: Fri, 29 Apr 2016 19:04:00 +0000
Subject: [GAP Forum] TestPackage and arbitrary message
Message-ID: <5723B020.4010400@rezozer.net>
Hello Forum:
I am looking for a GAP way to perform GAP package installation tests with reproducible output
(as in Test files, section 7.9 in the Reference Manual): TestPackage is certainly what
I am looking for. Unfortunately, TestPackage outputs arbitrary messages (or not) when
the tests succeed, something as:
GRAPE package: testall.tst
GAP4stones: 6
where the stones number is arbitrary (as CPU time can be) ---
and sometime, there is no message at all. In practice, I place the TestPackage
in a Test file (see above) and I launch something as
echo "QUIT_GAP(Test(\"d/t/makecheck.tst\"));" | gap -A -q -T
Is there a way to silence TestPackage in case of success ?
For now, I use TestDirectory :
echo "QUIT_GAP(TestDirectory(\"d/t\"));" | gap -A -q -T
which seems to be blind to these messages.
Thanks,
Jerome
From caj21 at st-andrews.ac.uk Wed May 4 20:15:36 2016
From: caj21 at st-andrews.ac.uk (Christopher Jefferson)
Date: Wed, 4 May 2016 19:15:36 +0000
Subject: [GAP Forum] TestPackage and arbitrary message
In-Reply-To: <5723B020.4010400@rezozer.net>
References: <5723B020.4010400@rezozer.net>
Message-ID:
Not at the moment, but this is an area where I think we need to improve our output.
I would suggest writing a bug report on github.com/gap-system/gap , with a suggested new output. You could even work on a patch if you like.
Chris
On 29/04/2016, 20:04, "forum-bounces at gap-system.org on behalf of z060822400814a at rezozer.net" wrote:
>Hello Forum:
>
>I am looking for a GAP way to perform GAP package installation tests with reproducible output
>(as in Test files, section 7.9 in the Reference Manual): TestPackage is certainly what
>I am looking for. Unfortunately, TestPackage outputs arbitrary messages (or not) when
>the tests succeed, something as:
>
> GRAPE package: testall.tst
> GAP4stones: 6
>
>where the stones number is arbitrary (as CPU time can be) ---
>and sometime, there is no message at all. In practice, I place the TestPackage
>in a Test file (see above) and I launch something as
>
> echo "QUIT_GAP(Test(\"d/t/makecheck.tst\"));" | gap -A -q -T
>
>Is there a way to silence TestPackage in case of success ?
>
>For now, I use TestDirectory :
>
> echo "QUIT_GAP(TestDirectory(\"d/t\"));" | gap -A -q -T
>
>which seems to be blind to these messages.
>
>Thanks,
>Jerome
>
>
>_______________________________________________
>Forum mailing list
>Forum at mail.gap-system.org
>http://mail.gap-system.org/mailman/listinfo/forum
From f.alibabaee at gmail.com Tue May 10 14:39:12 2016
From: f.alibabaee at gmail.com (fahime babaee)
Date: Tue, 10 May 2016 14:39:12 +0100
Subject: [GAP Forum] Question
Message-ID:
Dear Forum
Let $H$ and $K$ be finitely generated subgroups of the free group $F(n)$
such that $H\subseteq K$. We Know that $K$ is a free group. Now we choose
basis for $K$ and $H$ and I want to rewrite the basis of $H$ in the chosen
basis of $K$. I can do this calculation with hand by using automaton of $K$
but it take a long time. How can I do this with GAP?
Fahime Alibabaei
PhD student of Pure Mathematics(Algebra) University of Porto.
From alexander.konovalov at st-andrews.ac.uk Wed May 11 21:45:06 2016
From: alexander.konovalov at st-andrews.ac.uk (Alexander Konovalov)
Date: Wed, 11 May 2016 20:45:06 +0000
Subject: [GAP Forum] Question
In-Reply-To:
References:
Message-ID:
FYI: cross-posted yesterday and answered today at http://math.stackexchange.com/questions/1779212/
Alexander
> On 10 May 2016, at 14:39, fahime babaee wrote:
>
> Dear Forum
>
> Let $H$ and $K$ be finitely generated subgroups of the free group $F(n)$
> such that $H\subseteq K$. We Know that $K$ is a free group. Now we choose
> basis for $K$ and $H$ and I want to rewrite the basis of $H$ in the chosen
> basis of $K$. I can do this calculation with hand by using automaton of $K$
> but it take a long time. How can I do this with GAP?
>
> Fahime Alibabaei
> PhD student of Pure Mathematics(Algebra) University of Porto.
From marek at mitros.org Fri May 13 15:30:49 2016
From: marek at mitros.org (Marek Mitros)
Date: Fri, 13 May 2016 16:30:49 +0200
Subject: [GAP Forum] Square root of cyclotomic real number
Message-ID:
Dear All,
I am doing following calculation and I need square root of cyclotomic
number being real number. Here is example below. Is there any workaround
for this ?
What I am doing I obtained vector v of complex number which not unit
length. In order to normalize it I perform following and I receive the
error. Do I need more knowledge about cyclotomic numbers ?
gap> v1:=v/Sqrt(v*ComplexConjugate(v));
Error, no method found! For debugging hints type ?Recovery from
NoMethodFound
Error, no 1st choice method found for `Sqrt' on 1 arguments called from
( )
(...)
gap> n:=E(20)-E(20)^9;
E(20)-E(20)^9
gap> RealPart(n);
E(20)-E(20)^9
gap> Sqrt(n);
Error, no method found! For debugging hints type ?Recovery from
NoMethodFound
Error, no 1st choice method found for `Sqrt' on 1 arguments called from
Regards,
Marek
From hulpke at fastmail.fm Fri May 13 17:15:52 2016
From: hulpke at fastmail.fm (Alexander Hulpke)
Date: Fri, 13 May 2016 10:15:52 -0600
Subject: [GAP Forum] Square root of cyclotomic real number
In-Reply-To:
References:
Message-ID:
Dear Forum, Dear Marek Mitros,
Sqrt (as a short hand for the ER cyclotomic) will only work for rational numbers. If you wanted a square root of a cyclotomic number you would need to factor x^2-a over a suitable cyclotomic field.
Best,
Alexander Hulpke
> On May 13, 2016, at 8:30 AM, Marek Mitros wrote:
>
> Dear All,
>
> I am doing following calculation and I need square root of cyclotomic
> number being real number. Here is example below. Is there any workaround
> for this ?
> What I am doing I obtained vector v of complex number which not unit
> length. In order to normalize it I perform following and I receive the
> error. Do I need more knowledge about cyclotomic numbers ?
>
> gap> v1:=v/Sqrt(v*ComplexConjugate(v));
>
> Error, no method found! For debugging hints type ?Recovery from
> NoMethodFound
>
> Error, no 1st choice method found for `Sqrt' on 1 arguments called from
>
> ( )
>
> (...)
>
> gap> n:=E(20)-E(20)^9;
>
> E(20)-E(20)^9
>
> gap> RealPart(n);
>
> E(20)-E(20)^9
>
> gap> Sqrt(n);
>
> Error, no method found! For debugging hints type ?Recovery from
> NoMethodFound
>
> Error, no 1st choice method found for `Sqrt' on 1 arguments called from
>
>
> Regards,
>
> Marek
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum
From saeidi.amin at gmail.com Sat May 14 16:25:53 2016
From: saeidi.amin at gmail.com (Amin Saeidi)
Date: Sat, 14 May 2016 17:25:53 +0200
Subject: [GAP Forum] Character Table of semigroups
Message-ID:
Dear all,
I am trying to find the character tables of some finitely presented
semigroups, say for example:
.
It is an inverse semigroup of order 14. I can Define this semigroup in GAP
4.8.3 but I fail to find the character table:
*gap> IsInverseSemigroup(S);*
*true*
*gap> CharacterTableOfInverseSemigroup(S);*
*Error, no method found! For debugging hints type ?Recovery from
NoMethodFound*
*Error, no 1st choice method found for `CharacterTableOfInverseSemigroup'
on 1 arguments called from*
*( )*
* called from read-eval loop at line 87 of *stdin**
*you can 'quit;' to quit to outer loop, or*
*you can 'return;' to continue*
I thought this command may only work for monoids, so I considered a monoid
of order 15 but it didn't work either. However it works for some other
monoids. For instance the command gives the character table of S if I
write
*S:=SymmetricInverseMonoid(3); *
I will be grateful to let me know if it is a bug or I am doing something
wrong.
Best regards,
Amin
From marek at mitros.org Mon May 16 20:34:14 2016
From: marek at mitros.org (Marek Mitros)
Date: Mon, 16 May 2016 21:34:14 +0200
Subject: [GAP Forum] Square root of cyclotomic real number
In-Reply-To: