# 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.

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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

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.

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Thanks! Can you point me a reference on how to apply the patches?

( 2011-06-22 09:06:48 -0600 )edit