Degree() method of permutation group should (always) return a sage integer

[sagetrac-nborie]

There is some cases for which the degree method for PermutationGroup return a GapElement and not a sage integer.

sage: G = PermutationGroup([[(1,2,3,4)]])
sage: type(G.degree())
<type 'int'>
sage: H = G._gap_()
sage: H
Group( [ (1,2,3,4) ] )
sage: I = PermutationGroup(gap_group=H)
sage: type(I.degree())
<class 'sage.interfaces.gap.GapElement'>
sage: I == G
True
sage: G = TransitiveGroup(6,3)
sage: type(I.degree())
<class 'sage.interfaces.gap.GapElement'>

CC: @sagetrac-sage-combinat

Component: group theory

Issue created by migration from https://trac.sagemath.org/ticket/10883

[sagetrac-nborie]

Attachment: trac_10883_degree_type_permutationgroup-nb.patch.gz

[sagetrac-nborie]

comment:1

That is a very small bug... It came out when running another feature over Transitive Groups coming from the Gap database. I propose a very small patch to fix that (as Integer ring is already imported in the file permgroup.py). As I don't really know how this deserves to be done and documented, feel free to give advises and comments to fix it.

[sagetrac-nborie]

comment:2

Whhaaaaa!

I managed to report a bug which is not in Sage!

The quoting behavior was obtained with a very special state of Sage-Combinat. Effectively, with no patch applied, there is no problem. The method works fine.

sage: G = TransitiveGroup(6,3)
sage: type(G.degree())
<type 'sage.rings.integer.Integer'>
sage: G = PermutationGroup([[(1,2,3,4)]])
sage: H = G._gap_()
sage: I = PermutationGroup(gap_group=H)
sage: type(I.degree())
<type 'sage.rings.integer.Integer'>

I just realize it when the buildbot said the apply failed... For this reason, I think this ticket should be closed.