[GAP Forum] Forum Digest, Vol 86, Issue 6
Sara Radfar
sararadfarss at gmail.com
Mon Jan 17 13:27:01 GMT 2011
Dear All,
How we can by GAP conlude all automorphism group $A_7 timesA_7$?
Thanks,
Sara
On 1/16/11, forum-request at gap-system.org <forum-request at gap-system.org> wrote:
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> Today's Topics:
>
> 1. Re: Changing memory allocation for GAP
> (Asst. Prof. Dmitrii (Dima) Pasechnik)
> 2. why zoo? (Igor Korepanov)
> 3. how TzGo worked with us (Igor Korepanov)
> 4. Re: why zoo? (Frank L?beck)
> 5. Re: why zoo? (Asst. Prof. Dmitrii (Dima) Pasechnik)
> 6. Re: Changing memory allocation for GAP (Frank L?beck)
> 7. Re: how TzGo worked with us (Alexander Hulpke)
> 8. Analogue of IsFFEMatrixGroup for matrix groups over ZmodnZ
> (Max Horn)
> 9. Re: Analogue of IsFFEMatrixGroup for matrix groups over
> ZmodnZ (Alexander Hulpke)
> 10. Creating block matrices (Katie Morrison)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 12 Jan 2011 18:09:05 -0800
> From: "Asst. Prof. Dmitrii (Dima) Pasechnik" <dima at ntu.edu.sg>
> To: Sandeep Murthy <sandeepr.murthy at gmail.com>
> Cc: GAP forum <forum at gap-system.org>
> Subject: Re: [GAP Forum] Changing memory allocation for GAP
> Message-ID:
> <AANLkTi=jRoG-pKmdrSjSkskLXBUPE4a6oPYbnE=bcDCs at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Dear Sandeep,
> it looks as if you start GAP in a wrong way.
> (cause these > Error, file "-L" must exist and be readable
>> Error, file "-m" must exist and be readable
>> Error, file "128m" must exist and be readable
>> Error, file "-o" must exist and be readable
>> Error, file "512m" must exist and be readable
> things are mangled details of command line arguments...)
>
> One way that works is to start it in a Terminal window.
> Another is to use a special MacOSX application.
>
> Hope this helps,
> Dmitrii
>
> On 12 January 2011 12:29, Sandeep Murthy <sandeepr.murthy at gmail.com> wrote:
>> Hello.
>>
>> Is there a command for starting GAP from the command line to
>> open with a higher memory allocation, like 256 MB, than the standard
>> one?
>>
>> I use GAP v.4.4.12 on Mac OS Leopard. At present, when I start GAP
>> I see the following:
>>
>> --------
>>
>> Loading the library. Please be patient, this may take a while.
>> GAP4, Version: 4.4.12 of 17-Dec-2008, i686-apple-darwin9.6.0-gcc
>> Components: small 2.1, small2 2.0, small3 2.0, small4 1.0, small5 1.0,
>> small6 1.0, small7 1.0, small8 1.0, small9 1.0, small10 0.2,
>> id2 3.0, id3 2.1, id4 1.0, id5 1.0, id6 1.0, id9 1.0, id10
>> 0.1,
>> trans 1.0, prim 2.1 loaded.
>> Packages: AutPGrp 1.2, CTblLib 1.1.3, TomLib 1.1.4, FactInt 1.5.2,
>> GAPDoc 1.2 loaded.
>> Error, file "-L" must exist and be readable
>> Error, file "-m" must exist and be readable
>> Error, file "128m" must exist and be readable
>> Error, file "-o" must exist and be readable
>> Error, file "512m" must exist and be readable
>>
>> --------
>>
>> I run search algorithms on groups of exponential complexity, and they
>> are intrinsically slow. But I'm hoping that by using a higher initial
>> memory allocation, for practical purposes, my programs will cover
>> more of the search space than they have so far.
>>
>> Sincerely, Sandeep.
>>
>>
>> _______________________________________________
>> Forum mailing list
>> Forum at mail.gap-system.org
>> http://mail.gap-system.org/mailman/listinfo/forum
>>
>
>
>
> --
> Dmitrii Pasechnik
> -----
> DISCLAIMER: Any text following this sentence does not constitute a
> part of this message, and was added automatically during transmission.
>
> CONFIDENTIALITY: This email is intended solely for the person(s) named and
> may be confidential and/or privileged. If you are not the intended
> recipient, please delete it, notify us and do not copy, use, or disclose its
> content. Thank you.
>
> Towards A Sustainable Earth: Print Only When Necessary
>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 13 Jan 2011 10:54:22 +0300
> From: Igor Korepanov <paloff at ya.ru>
> To: forum at gap-system.org
> Subject: [GAP Forum] why zoo?
> Message-ID: <491691294905262 at web47.yandex.ru>
> Content-Type: text/plain
>
> Just one more question: is .zoo a somehow preferred way of archiving for GAP
> people? And why so if .tar.bz2 is so evidently better?
>
> Igor
>
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 13 Jan 2011 11:22:21 +0300
> From: Igor Korepanov <paloff at ya.ru>
> To: forum at gap-system.org
> Subject: [GAP Forum] how TzGo worked with us
> Message-ID: <191761294906941 at web4.yandex.ru>
> Content-Type: text/plain
>
> And still one more comment: we calculated yesterday the fundamental group of
> the 4-dimensional torus, which is, as everybody knows, the *abelian* group
> with 4 generators. That is, the Fp Group with 4 generators and 6 relation of
> type a * b * a^-1 * b^-1 .
>
> And all that was happily present in our GAP result, but besides that, there
> was one more redundant relation which we could derive manually from 6
> others, but the TzGo algorithm apparently could not!
>
> We used some stuff of our own to define this fundamental group and then the
> usual TzGo command to simplify it.
>
> Of course I've heard of undecidable problems and stuff (as I am currently
> employed as a university lecturer, like many people on this forum). But this
> particular problem must be decidable (here I searched Internet for a
> suitable English interjection like "er?" to end my letter, but found only
> some strange "Ekh-ma" http://en.wikipedia.org/wiki/Ekh_%28expression%29 ) ?
>
> Best wishes,
>
> Igor
>
>
>
> ------------------------------
>
> Message: 4
> Date: Thu, 13 Jan 2011 10:37:54 +0100
> From: Frank L?beck <frank.luebeck at math.rwth-aachen.de>
> To: forum at gap-system.org
> Subject: Re: [GAP Forum] why zoo?
> Message-ID: <20110113093754.GA19326 at beteigeuze>
> Content-Type: text/plain; charset=iso-8859-1
>
> On Thu, Jan 13, 2011 at 10:54:22AM +0300, Igor Korepanov wrote:
>> Just one more question: is .zoo a somehow preferred way of archiving for
>> GAP people? And why so if .tar.bz2 is so evidently better?
>
> But all of our archives are provided in .zoo, .tar.gz, .tar.bz2 and -win.zip
> format. You are free to use what you like most!
>
> .tar.bz2 is not "evidently better", e.g. it does not unpack text files
> under Windows/DOS with the native line break convention, and it is much
> slower to unpack them compared to, say, .tar.gz.
>
> See
> http://www.gap-system.org/Download/formats.html
> for more details.
>
> Best regards,
> Frank L?beck
>
> --
> /// Dr. Frank L?beck, Lehrstuhl D f?r Mathematik, Templergraben 64, ///
> \\\ 52062 Aachen, Germany \\\
> /// E-mail: Frank.Luebeck at Math.RWTH-Aachen.De ///
> \\\ WWW: http://www.math.rwth-aachen.de/~Frank.Luebeck/ \\\
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Thu, 13 Jan 2011 01:58:45 -0800
> From: "Asst. Prof. Dmitrii (Dima) Pasechnik" <dima at ntu.edu.sg>
> To: Igor Korepanov <paloff at ya.ru>
> Cc: "forum at gap-system.org" <forum at gap-system.org>
> Subject: Re: [GAP Forum] why zoo?
> Message-ID:
> <AANLkTik6umPeM+FwevF26x+bwatfWBOyvW=FZPpSyc-Q at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Igor,
> .zoo is an old format, historically the first GAP was using, exclusively.
>
> About 10 years ago there were long discussions on this list whether one
> should use other formats, and common sense prevailed, so .zoo is no longer
> the only format used.
> Perhaps .zoo will be retired at some point...
>
> On 12 January 2011 23:54, Igor Korepanov <paloff at ya.ru> wrote:
>> Just one more question: is .zoo a somehow preferred way of archiving for
>> GAP people? And why so if .tar.bz2 is so evidently better?
>>
>> Igor
>>
>> _______________________________________________
>> Forum mailing list
>> Forum at mail.gap-system.org
>> http://mail.gap-system.org/mailman/listinfo/forum
>>
>
>
>
> --
> Dmitrii Pasechnik
> -----
> DISCLAIMER: Any text following this sentence does not constitute a
> part of this message, and was added automatically during transmission.
>
> CONFIDENTIALITY: This email is intended solely for the person(s) named and
> may be confidential and/or privileged. If you are not the intended
> recipient, please delete it, notify us and do not copy, use, or disclose its
> content. Thank you.
>
> Towards A Sustainable Earth: Print Only When Necessary
>
>
>
> ------------------------------
>
> Message: 6
> Date: Thu, 13 Jan 2011 17:41:18 +0100
> From: Frank L?beck <frank.luebeck at math.rwth-aachen.de>
> To: Sandeep Murthy <sandeepr.murthy at gmail.com>, forum at gap-system.org
> Subject: Re: [GAP Forum] Changing memory allocation for GAP
> Message-ID: <20110113164117.GB26842 at beteigeuze>
> Content-Type: text/plain; charset=iso-8859-1
>
> On Wed, Jan 12, 2011 at 08:29:24PM +0000, Sandeep Murthy wrote:
>> Is there a command for starting GAP from the command line to
>> open with a higher memory allocation, like 256 MB, than the standard
>> one?
>>
>> I use GAP v.4.4.12 on Mac OS Leopard. At present, when I start GAP
>> I see the following:
>>
>> --------
>>
>> Loading the library. Please be patient, this may take a while.
>> GAP4, Version: 4.4.12 of 17-Dec-2008, i686-apple-darwin9.6.0-gcc
>> Components: small 2.1, small2 2.0, small3 2.0, small4 1.0, small5 1.0,
>> small6 1.0, small7 1.0, small8 1.0, small9 1.0, small10 0.2,
>> id2 3.0, id3 2.1, id4 1.0, id5 1.0, id6 1.0, id9 1.0, id10
>> 0.1,
>> trans 1.0, prim 2.1 loaded.
>> Packages: AutPGrp 1.2, CTblLib 1.1.3, TomLib 1.1.4, FactInt 1.5.2,
>> GAPDoc 1.2 loaded.
>> Error, file "-L" must exist and be readable
>> Error, file "-m" must exist and be readable
>> Error, file "128m" must exist and be readable
>> Error, file "-o" must exist and be readable
>> Error, file "512m" must exist and be readable
>>
>
>
> Dear Sandeep Murphy, dear Forum,
>
> To find an explaination in the GAP documentation type
>
> ?command line options
>
> into your GAP session. If one of the arguments in your call of GAP is
> a file name, then all further arguments are also interpreted as file names.
>
> So you should call GAP like:
> gap -m 128m -o 512m [maybe more options here] file1 file2 ...
>
> Using the -m option with a larger amount of memory does usually not give
> a big performance advantage. But using a higher value with the -o option
> causes that you see a message of form
>
> exceeded the permitted memory (`-o' command line option) at
> [...]
> brk>
>
> later than with the default value. (You can type 'return;' at that
> brk-prompt, then GAP doubles the value of the -o option.)
> Nevertheless, it does not make sense to specify with -o more memory than
> your GAP job has available as physical memory.
>
> With best regards,
> Frank L?beck
>
> --
> /// Dr. Frank L?beck, Lehrstuhl D f?r Mathematik, Templergraben 64, ///
> \\\ 52062 Aachen, Germany \\\
> /// E-mail: Frank.Luebeck at Math.RWTH-Aachen.De ///
> \\\ WWW: http://www.math.rwth-aachen.de/~Frank.Luebeck/ \\\
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Thu, 13 Jan 2011 10:20:17 -0700
> From: Alexander Hulpke <hulpke at math.colostate.edu>
> To: gap forum <forum at gap-system.org>
> Subject: Re: [GAP Forum] how TzGo worked with us
> Message-ID: <3196FBA1-3829-4234-A59D-9BC51E350DF3 at math.colostate.edu>
> Content-Type: text/plain; charset=us-ascii
>
>
>
> Dear Forum,
>
> On Jan 13, 2011, at 1/13/11 1:22, Igor Korepanov wrote:
>
>> And still one more comment: we calculated yesterday the fundamental group
>> of the 4-dimensional torus, which is, as everybody knows, the *abelian*
>> group with 4 generators. That is, the Fp Group with 4 generators and 6
>> relation of type a * b * a^-1 * b^-1 .
>>
>> And all that was happily present in our GAP result, but besides that,
>> there was one more redundant relation which we could derive manually from
>> 6 others, but the TzGo algorithm apparently could not!
>
> TzGo (the Tietze transformations command) uses a couple of heuristics, based
> on length criteria, to shorten a presentation, in particular if it was
> obtained from rewriting to a subgroup. It does not aim to do a systematic
> search for all redundancies. The primary aim is to get a presentation
> shorter with a moderate amount of effort, not to get an irredundant
> presentation or cover the largest possible class of decidable problems. It
> is clearly not optimal, but adding further attempts might cause an overall
> slowdown in other situations.
>
> Thus I'm not surprised that thinking (or even other algorithms that would be
> willing to devote more time) can produce better results in particular
> situations.
>
> Best wishes,
>
> 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
>
>
>
>
>
>
> ------------------------------
>
> Message: 8
> Date: Fri, 14 Jan 2011 15:24:16 +0100
> From: Max Horn <max at quendi.de>
> To: GAP Forum <Forum at gap-system.org>
> Subject: [GAP Forum] Analogue of IsFFEMatrixGroup for matrix groups
> over ZmodnZ
> Message-ID: <01D99A4D-2E0A-46D6-BCA3-8B8D4163A180 at quendi.de>
> Content-Type: text/plain; charset=us-ascii
>
> Dear GAP forum
>
> is there an analogue for IsFFEMatrixGroup and FieldOfMatrixGroup for groups
> over ZmodnZ ? Something like IsZmodnZMatrixGroup and RingOfMatrixGroup ? I
> didn't find anything like that. If it doesn't exist, how would I best go
> about adding those?
>
> Background: I'd like to install my own methods for e.g. NiceMonomorphism for
> matrix groups over ZmodnZ. To illustrate why: for GL(3, Z/36Z), GAP
> currently finds a perm rep on 39312 points, my code finds one on 758 points
> (it doesn't do anything fancy or new, mind you)
>
> For now, I just "manually" use SetNiceMonomorphism on my groups, but I
> thought it would be kinda nice to properly hook this into GAP (so that maybe
> it could even be integrated in a package or GAP itself one day).
>
>
> Cheers,
> Max
>
>
>
>
> ------------------------------
>
> Message: 9
> Date: Fri, 14 Jan 2011 10:03:32 -0700
> From: Alexander Hulpke <hulpke at math.colostate.edu>
> To: Max Horn <max at quendi.de>
> Cc: GAP Forum <Forum at gap-system.org>
> Subject: Re: [GAP Forum] Analogue of IsFFEMatrixGroup for matrix
> groups over ZmodnZ
> Message-ID: <965B2533-1AC7-486E-ACAA-32BD16BCFC42 at math.colostate.edu>
> Content-Type: text/plain; charset=us-ascii
>
>
>
> Dear Forum,
>
> On Jan 14, 2011, at 1/14/11 7:24, Max Horn wrote:
>
>> is there an analogue for IsFFEMatrixGroup and FieldOfMatrixGroup for
>> groups over ZmodnZ ? Something like IsZmodnZMatrixGroup and
>> RingOfMatrixGroup ? I didn't find anything like that. If it doesn't exist,
>> how would I best go about adding those?
>
> Assuming you want to catch the case for nonprime n, the equivalent for
> IsFFEMatrixGroup would be
> IsZmodnZObjNonprimeCollCollColl and IsMatrixGroup
>
> To get the underlying ring, you could use
> DefaultRing(Flat(GeneratorsOfGroup(g)));
>
> Best wishes,
>
> Alexander Hulpke
>
>
>
>
>
>
>
> ------------------------------
>
> Message: 10
> Date: Sun, 16 Jan 2011 22:21:10 -0600
> From: Katie Morrison <kmorris2 at gmail.com>
> To: forum at gap-system.org
> Subject: [GAP Forum] Creating block matrices
> Message-ID:
> <AANLkTikx8fOUPG=ob1FxdQCpXikqYnk=-baCpcSLJnvk at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi all, I was wondering if there's an efficient way to create the subgroup
> of GL(2n, q) consisting of block matrices of the form:
> [A 0
> B C]
> where A and C are in GL(n,q) and B is in M(n,q) (i.e. B is an arbitrary nxn
> matrix). Thanks for the help.
>
> Katie
>
>
> ------------------------------
>
> _______________________________________________
> Forum mailing list
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>
> End of Forum Digest, Vol 86, Issue 6
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