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Questions tagged [gap-system]

GAP (Groups, Algorithms and Programming) is an open source mathematical software system for discrete computational algebra (https://www.gap-system.org). Ask here non-mathematical questions about programming in GAP; for mathematical questions use the (gap) tag at Mathematics Q&A site: https://math.stackexchange.com/questions/tagged/gap. Other places to ask about GAP are the GAP Forum and GAP Support: https://www.gap-system.org/Contacts/Forum/forum.html

This is the tag for questions related to the computational algebra system GAP.

GAP (Groups, Algorithms and Programming) is a system for computational discrete algebra, with particular emphasis on Computational Group Theory. It provides a programming language, a library of thousands of functions implementing algebraic algorithms written in the GAP language as well as large data libraries of algebraic objects. GAP is used in research and teaching for studying groups and their representations, rings, vector spaces, algebras, combinatorial structures, and more.

If you want to ask a question in this category, please note that there are well-established support channels for GAP users such as GAP Forum and GAP Support which may be more suitable places for such questions with a different (though possibly intersecting) audience, and with a different response rate (which may be faster or slower, dependently on your question). While there may be GAP users and some authors of GAP and/or its packages among the users of this Q&A site, please do not assume that the question on GAP asked here will necessarily be noticed by them.

It may also happen that your question is already answered in the Frequently Asked Questions section of the GAP website or in the GAP Forum (to search GAP Forum archives, click here), or under the "gap" tag on the Mathematics Q&A website.

Finally, if you think that you have discovered a bug in the GAP system, the recommended way to report it is to use the GAP issue tracker on GitHub. Many packages have their own issue trackers, which you can find following the links here.

56 questions
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How do you use GAP to identify a group?

How do you use GAP to identify the name of a group from its multiplication table? I know that you can define a group from a set of generators, and then look for the group in the set of internal tables: gap> g := Group([ (1,2), (1,2,3,4,5) ]); …
wye.bee
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Return elements of the Groebner Basis as they are found

This question could refer to any computer algebra system which has the ability to compute the Groebner Basis from a set of polynomials (Mathematica, Singular, GAP, Macaulay2, MatLab, etc.). I am working with an overdetermined system of polynomials…
mboratko
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Mathematica and GAP: Is there an interface?

Although the Abstract Algebra Add-on is a beautiful package for Mathematica, imo there is nothing that beats GAP, at least not for Group Theory. When I looked at Sage a few years ago, I found that said to have an interface with Mma but when I looked…
nilo de roock
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How do you print to a text file in GAP without linebreaks?

Minimum working example: x:=Indeterminate(Rationals,"x"); f:=Sum([1..1000],i->x^i); PrintTo("~/temp.txt",f); It prints to temp.txt the…
Rebecca J. Stones
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How do you control text formatting when launching GAP scripts from the command line?

I would like to understand GAP's behaviour when I launch a script from the command line, for example $ gap mytest.gap as opposed to calling it from inside GAP gap> Read("mytest.gap"); In particular, I've tried to suppress automatic formatting with…
Giles Gardam
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4
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How can I call GAP functions from a shell script?

I want to get the result of a function of the GAP software. This is an interactive command line tool mainly for mathematician who work on group theory related topics. The documentation/faq states about 8.1: Can I call GAP functions from another…
Hotschke
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How do you change the current directory in GAP?

How do you change the current directory in GAP? I wrote: gap> ChangeDirectoryCurrent("Users/anymuanalifah/Documents") and I received an error. I use Mac OS X if that matters.
AnyMu
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Getting data from GAP in a Python program - Sage or without Sage?

I have a Python parser that can read from and write to static JSON files (containing JSON objects that map to Python dicts) on my local machine. The properties of these objects related to finite group objects in the GAP Small Groups Library. Is…
user997225
3
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1 answer

How can you compute a simplified Groebner basis in GAP?

I tried to use Buchberger's Algorithm (see this or this) to compute a Groebner basis for an ideal in rational field. Here is my GAP script: F := Rationals; R := PolynomialRing( F, [ "x", "y", "z" ]); x := IndeterminatesOfPolynomialRing(R)[1]; y :=…
jscoot
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Linear Diophantine Equations with Restriction in the GAP System

I am searching for a way to use the GAP System to find a solution of a linear Diophantine equation over the non-negative integers. Explicitly, I have a list L of positive integers for each of which there exists a solution of the linear Diophantine…
Dylan C. Beck
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How to export results obtained by "Display" in GAP to a .txt file

I started to use GAP for computing table of characters for symmetric groups. I would like to export the result of the following Display(CharacterTable(SymmetricGroup(4))); into a .txt file (which later on I would like to import to Mathematica). My…
mikis
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How do you use GAP in batch mode?

I can't seem to figure out how to use the GAP computer algebra system (for example, if I have a python script, I can do python script.py > /tmp/python_output.csv) I can't seem to find any info in the GAP documentation [I am sure it is there…
Igor Rivin
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Working with holes in the lists [GAP SYSTEM]

I have a question regarding holes in the lists. Assume that I have the following code: gap> l:=[2,3,,5]; [ 2, 3,, 5 ] gap> for i in [1..Size(l)] do > Print(l[i],"\n"); > od; 2 3 Error, List Element: [3] must have an assigned value in Print(…
Vasyl Laver
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Bitwise Operators in GAP

Is one able to to use bitwise operators in the GAP programming language? For example, in Python one can do the following: a = 60 # 60 = 0011 1100 b = 13 # 13 = 0000 1101 c = 0 c = a & b; # 12 = 0000 1100 c = a | b; …
Dan P.
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Radiroot package in GAP generating errors

When I run the following commands g := UnivariatePolynomial(Rationals, [12,-5,0,0,0,1]); RootsOfPolynomialAsRadicals(g); I get this error *** too many arguments: ...;,nf=nfinit([f,nfbasis(f,1)]);fac=lift(nffact *** …
Ben
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