[GAP Forum] RE: Forum Digest, Vol 6, Issue 4

Rashid Ali rashid at jinnah.edu.pk
Wed Jun 2 07:06:10 BST 2004


Dear Forum Members

I am working on computations of Self-Connected and H-Connected transversals of a group G. Since total number of transversals for a finite group G with a subgroup H = Order(H)^Index(G,H). I've designed an algorithm that searches self-connected and H-connected transversals. It works properly for small groups but for large gooups say for example when Order(G)=1792, and Order(H)=64, it perform computations for many hours but it quits gap session automatically leaving the executation incomplete, and displays following message that I'm unable to understand:

   0 [main] gapw95 1116 handle_exceptions: Exception: STATUS_ACCESS_VIOLATION

  1062 [main] gapw95 1116 stackdump: Dumping stack trace to gapw95.exe.stackdump

I can't understand how to resolve this problem

Regards

Rashid Ali

-----Original Message-----
From: forum-bounces at gap-system.org
[mailto:forum-bounces at gap-system.org]On Behalf Of
forum-request at gap-system.org
Sent: Monday, May 31, 2004 12:38 PM
To: forum at gap-system.org
Subject: Forum Digest, Vol 6, Issue 4


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Today's Topics:

   1. Re: Forum Digest, Vol 6, Issue 3 (Email problems)
      (Michael Hartley)
   2. help with polycyclic (Ayan Mahalanobis)
   3. Re: help with polycyclic (Werner Nickel)
   4. A service for GAP remote access (Lev Pliner)
   5. Re: A service for GAP remote access (Sebastian Freundt)
   6. Re: A service for GAP remote access (J.F. Huesman)
   7. Re: A service for GAP remote access (Lev Pliner)
   8. REPSN package (Charles Wright)
   9. RE: MatrixOfAction (quagroup)
  10. Re: A service for GAP remote access (Lev Pliner)


----------------------------------------------------------------------

Message: 1
Date: Thu, 20 May 2004 00:41:53 +0800
From: "Michael Hartley" <Michael.Hartley at nottingham.edu.my>
Subject: [GAP Forum] Re: Forum Digest, Vol 6, Issue 3 (Email problems)
To: <forum at gap-system.org>
Message-ID: <s0abfedd.059 at gwmail.nottingham.edu.my>
Content-Type: text/plain; charset=US-ASCII


I am currently having problems with my computer. IS is working on the
issue. Until the problem is solved, I may not be able to read all my
email.

With apologies,
Michael Hartley



------------------------------

Message: 2
Date: Thu, 20 May 2004 12:20:54 -0400
From: Ayan Mahalanobis <amahalan at fau.edu>
Subject: [GAP Forum] help with polycyclic
To: gap-forum at dcs.st-and.ac.uk
Message-ID: <40ACDAE6.5080204 at fau.edu>
Content-Type: text/plain; charset=us-ascii; format=flowed

Hello,
I am new in GAP and was trying to come up with a polycyclic presentation 
of a 2-group. I couldn't get it to work.
The message I am getting is this

gap>UpdatePolycyclicCollector(flt);
gap> IsConfluent(flt);
Inconsistency at 4 3 2
false

The message makes no sense to me. I can provide with more details 
including the Fp definition of the group, if necessary.

Thanks and regards
Ayan



------------------------------

Message: 3
Date: Thu, 20 May 2004 23:50:57 +0200
From: Werner Nickel <nickel at mathematik.tu-darmstadt.de>
Subject: Re: [GAP Forum] help with polycyclic
To: Ayan Mahalanobis <amahalan at fau.edu>
Cc: gap-forum at dcs.st-and.ac.uk
Message-ID: <20040520215057.GA7336 at mathematik.tu-darmstadt.de>
Content-Type: text/plain; charset=us-ascii



> Hello,
> I am new in GAP and was trying to come up with a polycyclic presentation 
> of a 2-group. I couldn't get it to work.
> The message I am getting is this
> 
> gap>UpdatePolycyclicCollector(flt);
> gap> IsConfluent(flt);
> Inconsistency at 4 3 2
> false

A polycyclic presentation called confluent if any two words in reduced
form (i.e. x1^e1*x2^e2*...*xn^en) define different elements of the
group given by the polycyclic presentation.  The reduced form is used
to check equality of elements.  Therefore, confluence of the
polycyclic presentation is essential for being able to perform
arithmetic in the group.  

There are a number of reason why your presentation may not be
confluent.  If you send me the presentation, I am happy to have a
look. 

All the best
Werner Nickel




------------------------------

Message: 4
Date: Mon, 24 May 2004 17:34:34 +0600
From: "Lev Pliner" <pliner at sky.ru>
Subject: [GAP Forum] A service for GAP remote access
To: <forum at gap-system.org>
Message-ID: <001501c44183$1682f960$b90d72d9 at lsp>
Content-Type: text/plain;	charset="koi8-r"

Dear forum users.

My name is Lev Pliner. I'm a PhD student at Ural State University,
Katerinburg, Russia. I've rendered a server that allows to remotely run GAP
(rGAP) and a simple client for it (cGAP).

I used cygwin/gcc, so I hope it may be compiled/linked under linux. If it
so, the mentioned software allows to use GAP kernel run under linux with all
packages using a client run under windows. A client based upon readline
library so many customizations can be done (see man readline for further
information).

I can send a singlethreaded version of server; multithreaded is ready but
still has a lot of bugs.

Lev.



------------------------------

Message: 5
Date: Mon, 24 May 2004 20:35:18 +0000
From: Sebastian Freundt <freundt at math.TU-Berlin.DE>
Subject: Re: [GAP Forum] A service for GAP remote access
To: "Lev Pliner" <pliner at sky.ru>
Cc: forum at gap-system.org
Message-ID: <nhtwu31sgvt.fsf at mack.math.tu-berlin.de>
Content-Type: text/plain; charset=us-ascii


"Lev Pliner" <pliner at sky.ru> writes:

> Dear forum users.
>
> My name is Lev Pliner. I'm a PhD student at Ural State University,
> Katerinburg, Russia. I've rendered a server that allows to remotely run GAP
> (rGAP) and a simple client for it (cGAP).
[snip]

I'd like to try it. Is it available somewhere?

Greets
Sebastian Freundt



------------------------------

Message: 6
Date: Mon, 24 May 2004 17:05:08 -0700 (PDT)
From: "J.F. Huesman" <qphysics at yahoo.com>
Subject: Re: [GAP Forum] A service for GAP remote access
To: forum at gap-system.org
Message-ID: <20040525000508.81889.qmail at web51604.mail.yahoo.com>
Content-Type: text/plain; charset=us-ascii

Hello,
I run cygwin, solaris, redhat linux, and NeXT.
Is the service available, I would like to see about compiling it on different
platforms and seeing how it works.

J.F. Huesman
University of South Florida
Tampa, Florida


--- Lev Pliner <pliner at sky.ru> wrote:
> Dear forum users.
> 
> My name is Lev Pliner. I'm a PhD student at Ural State University,
> Katerinburg, Russia. I've rendered a server that allows to remotely run GAP
> (rGAP) and a simple client for it (cGAP).
> 
> I used cygwin/gcc, so I hope it may be compiled/linked under linux. If it
> so, the mentioned software allows to use GAP kernel run under linux with all
> packages using a client run under windows. A client based upon readline
> library so many customizations can be done (see man readline for further
> information).
> 
> I can send a singlethreaded version of server; multithreaded is ready but
> still has a lot of bugs.
> 
> Lev.
> 
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum


=====
For every credibility gap, there is a gullibility fill.
-- R. Clopton



------------------------------

Message: 7
Date: Tue, 25 May 2004 10:06:11 +0600
From: "Lev Pliner" <pliner at sky.ru>
Subject: Re: [GAP Forum] A service for GAP remote access
To: "Sebastian Freundt" <freundt at math.TU-Berlin.DE>,	"John Brinkman"
	<BRINKMJ at hope.ac.uk>
Cc: forum at gap-system.org
Message-ID: <003b01c4420d$9d5555c0$b90d72d9 at lsp>
Content-Type: text/plain; charset="iso-8859-1"

> I'd like to try it. Is it available somewhere?

1. Use following command to build rGAP (server):
gcc rpcGAP.c rpcGAP_s.c iGAP_ss.c rGAP_ss.c -lrpclib -orGAP

2. Use following command to build cGAP (client):
gcc rpcGAP.c rpcGAP_c.c iGAP_ss.c cGAP.c -lrpclib -lreadline -ocGAP

3. GAP root should be /usr/sbin/gap (or modifications should be done at
rGAP_ss.c).

4. Some source was taken from xGAP.

5. To quit client execution better type '?quit', not 'quit;' to close GAP.

6. If this work will be of intrest, I will send multithreaded version with
documentation (this version is not documented at all), including my plans
for further work.

Best wishes.
Lev.

------------------------------

Message: 8
Date: Tue, 25 May 2004 08:23:07 -0700
From: Charles Wright <wright at uoregon.edu>
Subject: [GAP Forum] REPSN package
To: GAP Forum <gap-forum at dcs.st-and.ac.uk>
Message-ID: <40B364DB.9040504 at uoregon.edu>
Content-Type: text/plain; charset=us-ascii; format=flowed

Dear GAP Forum members --

I am pleased to report acceptance of the GAP4 Package "Repsn" by Vahid 
Dabbaghian-Abdoly. The package deals with the computation of complex 
irreducible representations of finite groups and provides a combination 
of several heuristics for constructing the representations in question 
by inducing or extending representations of suitable subgroups (as an 
application of Clifford's Theorem).

It also includes a special treatment of perfect groups, with the effect 
that the functions of the package can compute a representation affording 
any irreducible group character of degree less than 32, with no 
restriction on the degree if the group is solvable.

The package will be included in the standard GAP package distribution 
and is available now from www.math.carleton.ca/~vdabbagh/gap/repsn.html.

Charles R.B. Wright



------------------------------

Message: 9
Date: Sat, 15 May 2004 02:42:06 +0200
From: "quagroup" <quagroup at hetnet.nl>
Subject: RE: [GAP Forum] MatrixOfAction
To: "Jan Draisma" <Jan.Draisma at unibas.ch>,	"GAP Forum"
	<GAP-Forum at dcs.st-and.ac.uk>
Message-ID:
	<03578DA00653CD418F5C3C16B7295A3802D062A5 at HNEXVS03.HETNET.LOCAL>
Content-Type: text/plain;	charset="Windows-1252"

Dear Jan,

Thanks for your report.
What you reported was indeed a bug, which will be fixed in the 
next bugfix. Temporarily you can fix it in your own copy of GAP
by loading the code below.
If you have any questions, please ask.

Best wishes,

Willem de Graaf

############################################################################
##
#M  DirectSumOfAlgebraModules( <list> )
#M  DirectSumOfAlgebraModules( <V>, <W> )
##
InstallMethod( DirectSumOfAlgebraModules,
        "for a list of algebra modules",
        true, [ IsDenseList ], 0,
        function( list )

    local   left_action,  right_action,  F,  fam,  type,  niceVF,
            gens,  zero,  i,  gV,  v,  be,  A,  B,  V,  W,  niceMod,
            BW;

    # There are two types of action on a direct sum: left and right.

    left_action:= function( x, tn )

        return ObjByExtRep( FamilyObj( tn ),
                       List( ShallowCopy( ExtRepOfObj( tn ) ), u -> x^u ) );
    end;

    right_action:= function( tn, x )

        return ObjByExtRep( FamilyObj( tn ),
                       List( ShallowCopy( ExtRepOfObj( tn ) ), u -> u^x ) );
    end;


    # We first make the family of the direct sum elements, and construct
    # a basis of the direct sum. Note that if the arguments do not
    # know how to compute bases, then the rewriting of direct sum elements
    # to normal
    # forms will fail. Hence we can assume that every module has a basis,
    # and therefore we have a basis of the direct sum as well.

    F:= LeftActingDomain( list[1] );
    fam:= NewFamily( "DirectSumElementsFam", IsDirectSumElement );
    type:= NewType( fam, IsPackedElementDefaultRep );
    fam!.directSumElementDefaultType:= type;
    fam!.zeroCoefficient:= Zero( F );
    fam!.constituentModules:= list;

    niceMod:= FullSparseRowSpace( F, Sum( List( list, Dimension ) ) );
    niceVF:= ElementsFamily( FamilyObj( niceMod ) );
    fam!.niceVectorFam:= niceVF;

    gens:= [ ];
    zero:= List( list, x -> Zero( x ) );
    for i in [1..Length(list)] do
        gV:= Basis( list[i] );
        for v in gV do
            be:= ShallowCopy( zero );
            be[i]:= v;
            Add( gens, be );
        od;
    od;

    if gens = [ ] then
        gens:= [ zero ];
    fi;

    gens:= List( gens, x -> ObjByExtRep( fam, x ) );
    for i in [1..Length(gens)] do
        gens[i]![2]:= true;
    od;

    # Now we make the direct sum, we need to consider a few cases...

    if IsLeftAlgebraModuleElementCollection( list[1] ) then
        if IsRightAlgebraModuleElementCollection( list[1] ) then

            if not ForAll( list, V ->
                       IsLeftAlgebraModuleElementCollection(V) and
                       IsRightAlgebraModuleElementCollection(V)) then
              Error("for all modules the algebra must act om the same side");
            fi;

            A:= LeftActingAlgebra( list[1] );
            B:= RightActingAlgebra( list[1] );
            if not ForAll( list, V ->
                       IsIdenticalObj( LeftActingAlgebra(V), A ) and
                       IsIdenticalObj( RightActingAlgebra(V), B ) )
             then Error("all modules must have the same left acting algebra" );
            fi;

            V:= BiAlgebraModuleByGenerators( A, B, left_action, right_action,
                           gens );
        fi;

        if not ForAll( list, IsLeftAlgebraModuleElementCollection ) then
            Error( "for all modules the algebra must act om the same side" );
        fi;

        A:= LeftActingAlgebra( list[1] );
        if not ForAll( list, V -> IsIdenticalObj( LeftActingAlgebra(V), A ) )
           then Error( "all modules must have the same left acting algebra" );
        fi;

        V:= LeftAlgebraModuleByGenerators( A, left_action, gens );
    else

        if not ForAll( list, IsRightAlgebraModuleElementCollection ) then
            Error( "for all modules the algebra must act om the same side" );
        fi;

        A:= RightActingAlgebra( list[1] );
        if not ForAll( list, V -> IsIdenticalObj( RightActingAlgebra(V), A ) )
           then Error( "all modules must have the same left acting algebra" );
        fi;

        V:= RightAlgebraModuleByGenerators( A, right_action, gens );
    fi;

    if IsZero( gens[1] ) then
        return V;
    fi;

    # We construct a basis `B' of the direct sum.
    # This is a basis of an algebra module, so it works via a delegate
    # basis, which is a basis of the module spanned by the elements `gens'.
    # We call this module `W', and `BW' will be a basis of `W'.
    # Now `W' works via a nice basis and we know the basis vectors of this
    # nice basis (namely all unit vectors). So we set the attribute `NiceBasis'
    # of `BW' to be the standard basis of the full row space.

    W:= VectorSpace( F, gens, "basis" );
    SetNiceFreeLeftModule( W, niceMod );
    B:= Objectify( NewType( FamilyObj( V ), IsFiniteBasisDefault and
                 IsBasisOfAlgebraModuleElementSpace and
                 IsAttributeStoringRep ), rec() );
    SetUnderlyingLeftModule( B, V );
    SetBasisVectors( B, GeneratorsOfAlgebraModule(V) );

    BW:= Objectify( NewType( FamilyObj( W ), IsBasisByNiceBasis and
                                            IsAttributeStoringRep ), rec() );
    SetUnderlyingLeftModule( BW, W );
    SetBasisVectors( BW, gens );
    SetNiceBasis( BW, Basis( niceMod ) );

    B!.delegateBasis:= BW;
    SetBasis( V, B );
    SetDimension( V, Length( gens ) );
    return V;


end );





------------------------------

Message: 10
Date: Mon, 31 May 2004 13:32:48 +0600
From: "Lev Pliner" <pliner at sky.ru>
Subject: Re: [GAP Forum] A service for GAP remote access
To: "J.F. Huesman" <qphysics at yahoo.com>, <forum at gap-system.org>
Message-ID: <000b01c446e1$795e5df0$b90d72d9 at lsp>
Content-Type: text/plain;	charset="iso-8859-1"

Have anybody tried to build the source?
Lev.

----- Original Message ----- 
From: "J.F. Huesman" <qphysics at yahoo.com>
To: <forum at gap-system.org>
Sent: Tuesday, May 25, 2004 6:05 AM
Subject: Re: [GAP Forum] A service for GAP remote access


> Hello,
> I run cygwin, solaris, redhat linux, and NeXT.
> Is the service available, I would like to see about compiling it on
different
> platforms and seeing how it works.
>
> J.F. Huesman
> University of South Florida
> Tampa, Florida
>
>
> --- Lev Pliner <pliner at sky.ru> wrote:
> > Dear forum users.
> >
> > My name is Lev Pliner. I'm a PhD student at Ural State University,
> > Katerinburg, Russia. I've rendered a server that allows to remotely run
GAP
> > (rGAP) and a simple client for it (cGAP).
> >
> > I used cygwin/gcc, so I hope it may be compiled/linked under linux. If
it
> > so, the mentioned software allows to use GAP kernel run under linux with
all
> > packages using a client run under windows. A client based upon readline
> > library so many customizations can be done (see man readline for further
> > information).
> >
> > I can send a singlethreaded version of server; multithreaded is ready
but
> > still has a lot of bugs.
> >
> > Lev.
> >
> > _______________________________________________
> > Forum mailing list
> > Forum at mail.gap-system.org
> > http://mail.gap-system.org/mailman/listinfo/forum
>
>
> =====
> For every credibility gap, there is a gullibility fill.
> -- R. Clopton
>
> _______________________________________________
> Forum mailing list
> Forum at mail.gap-system.org
> http://mail.gap-system.org/mailman/listinfo/forum



------------------------------

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End of Forum Digest, Vol 6, Issue 4
***********************************




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