Questions tagged [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, and large data libraries of algebraic objects.

Please note that GAP Forum or GAP Support may be more suitable places for questions about GAP: see http://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.

Suggestions on using the gap tag:

  • please use it for new questions which explicitly ask something about the GAP system. This will help other GAP users who are reading math.SE to discover your question;

  • please don't use it for retrospective tagging of answered or commented questions where the answers/comments use GAP but most likely same calculation could be performed with any general-purpose computer algebra system;

  • in other cases, please use it with certain discretion, dependently on the potential learning value of the content of the discussion for other GAP users.

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 are certainly 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 seen by the majority of GAP developers and package authors. On the other hand, research questions which may be of interest to wide ranks of GAP users are certainly welcomed here as well.

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).

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.

810 questions
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Product of elements in a list in GAP

I just started learning GAP and I'm trying to do simple exercises. The following problem is something I have not been able to figure out. So I found the character degrees of $S_4$ using the following…
user824863
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Arrow is in a finite linear combinations of paths of a Quiver

I am learning about GAP and QPA. I would like to know when a arrow is in a finite linear combinations of paths of a Quiver. For example: Q := Quiver(4,[[1,2],[2,4],[1,3],[3,4]]); KQ := PathAlgebra(Rationals, Q); AssignGeneratorVariables(KQ); elem…
Vasco
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Gap: Determinant with Indeterminate()

This is probably very easy but can't figure it out. How can I compute the determininant of a matrix with indeterminate entries in it? gap> a:=X(Rationals); x_1 gap> m:=[[a,0],[0,a]]; [ [ x_1, 0 ], [ 0, x_1 ] ] gap> DeterminantMat(m); Error, no…
diffset
  • 465
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Is there an easy way to find all possible string modules (using the GAP package QPA)?

I am trying to find all string modules of a given string algebra using the GAP package QPA. The aim is to have a list containing the strings corresponding to the string modules. As an example: For a quiver $Q$ with two vertices one loop $a$ at…
Bobior
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GAP — NullspaceModQ not working

I am using the GAP (Groups, Algorithms and Programming) system. For some reason the function NullspaceModQ (which is supposed to give a left kernel of matrix modulo a prime power $Q$) works incorrectly. While NullspaceModQ([[4]],8) correctly…
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Quiver and relations for a quotient algebra via QPA

Given a finite dimensional quiver algebra $B$ and a basic idempotent $e$. Is there a quick way to obtain the algebra B/BeB by quiver and relations using the GAP-package QPA? One way to do this is to obtain the module $B/BeB$ using…
Mare
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Define the image of a representation of a finitely presented group in GAP

Please note that the example below is just a baby case in which my problem occurs. Of course there is a simple workaround for my problem in this particular example, but I would like to apply this to more complicated finitely presented groups and…
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Conjugacy class of a tuple in GAP

I would like to know how to obtain the conjugacy class of some tuple in GAP, or how two know if two tuples are conjugate by an element of some group (permutation group, more especifically). I know that for unidimensional cases I can use IsConjugate…
MaríaCC
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finding the actions of semidirect products in GAP

I am a newbie in GAP, and I couldn't find how one can find the action of a semi direct product in GAP. Can anyone help me with it? More specifically, I am working with SmallGroup(720,774). GAP tells me that the group structure is $((C_3 \times…
Ellie
  • 21
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An element $\notin I$, any ideal is projected to zero.

I have rwo unrelated questions but I put them in one question because they occur in the same GAP session: In following code $x, y, z$ are already defined as indeterminates in the rationals. In following code: gap> P := PolynomialRing(Rationals,…
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Using function with multiple args over a list

So working in GAP, I have constructed a list, $L$, of the normal subgroups of a given group of interest (which I defined to be $G$). Now I want to construct a new list $Q$ which is to be comprised of the corresponding quotient groups $G/N$ given by…
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Run GAP calculation for fixed time

Is there a way to make gap stop a calculation after a certain amount of time? I'm using an algorithm which is not guaranteed to terminate. But on (small) cases it will be either stop in under a second or run forever. In the moment I start the…
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Hamiltonian groups in GAP

Is there any command in GAP to generate a Hamiltonian group of an order given? I'm looking for in GAP-Reference Manual, but i don't find anything. Bujalance, Etayo & Gamboa define a Hamiltonian group like a kind of group wich all subgroups are…
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Fixed points on right cosets in GAP

given a finite permutation group $G$ and a list of subgroups of $G$ list1. I want to compute the fixed points of $U$ acting on $G/V$ via right multiplication, where $U, V \in$ list1 (i.e. a submatrix of the table of marks of $G$ ). If the groups are…
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Remove one nesting level from a list of lists

I have a list with entries like e:=[[[1,2]],[[3,4]],[[5,6]]]; I want to remove double list brackets to get a list looking like result:=[[1,2],[3,4],[5,6]]; How can I do this in GAP?
S786
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