ASKSAGE: Sage Q&A Forum - Individual question feedhttp://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Wed, 22 Jun 2011 09:06:48 -0500Specifying cardinality for action of permutation grouphttp://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/In Magma, it is possible to create a permutation group with something like `G := PermutationGroup<n|relations>,` where $n$ is to be the cardinality of the set the group acts on. One needs this cardinality to use a GModule method. I would like to create such a group in Sage and then port it to Magma to create a GModule, but I always end up with a Magma element having too small a cardinality. Is it possible to specify such a cardinality in Sage? Can it be created as a subgroup of $S_n$? I did not have luck with that.
Tue, 21 Jun 2011 19:09:49 -0500http://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/Answer by Mike Hansen for <p>In Magma, it is possible to create a permutation group with something like <code>G := PermutationGroup<n|relations>,</code> where $n$ is to be the cardinality of the set the group acts on. One needs this cardinality to use a GModule method. I would like to create such a group in Sage and then port it to Magma to create a GModule, but I always end up with a Magma element having too small a cardinality. Is it possible to specify such a cardinality in Sage? Can it be created as a subgroup of $S_n$? I did not have luck with that.</p>
http://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/?answer=12454#post-id-12454In ticket 10335, there is a patch which will allow one to specify the domain of the permutation group (and hence its cardinality). For example, you'll be able to do something like
sage: P = PermutationGroup([[(1,2)], [(1,3),(2,4)]], domain=[1,2,3,4,5])
sage: P.degree()
5
where as now in Sage you would get `4` for the degree. This will also be passed on to Magma. I'm hoping that this will be in the next release of Sage.Wed, 22 Jun 2011 07:19:51 -0500http://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/?answer=12454#post-id-12454Comment by Cody for <p>In ticket 10335, there is a patch which will allow one to specify the domain of the permutation group (and hence its cardinality). For example, you'll be able to do something like </p>
<pre><code>sage: P = PermutationGroup([[(1,2)], [(1,3),(2,4)]], domain=[1,2,3,4,5])
sage: P.degree()
5
</code></pre>
<p>where as now in Sage you would get <code>4</code> for the degree. This will also be passed on to Magma. I'm hoping that this will be in the next release of Sage.</p>
http://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/?comment=21563#post-id-21563Thanks! Can you point me a reference on how to apply the patches?Wed, 22 Jun 2011 09:06:48 -0500http://ask.sagemath.org/question/8180/specifying-cardinality-for-action-of-permutation-group/?comment=21563#post-id-21563