#4521: Trivial permutation group enumeration bug
--------------------------+-------------------------------------------------
Reporter: kohel | Owner: joyner
Type: defect | Status: new
Priority: major | Milestone: sage-3.4
Component: group_theory | Resolution:
Keywords: |
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Changes (by mabshoff):
* cc: mhansen (added)
* milestone: => sage-3.4
Old description:
> 1. This gives an error:
>
> sage: G = PermutationGroup([])
> sage: G.list()
>
> 2. Permutation group should take an argument for the degree, e.g.:
>
> sage: G = PermutationGroup([],degree=4)
>
> 3. Permutation group should set the degree correctly:
>
> sage: G = PermutationGroup([[]])
> sage:
> sage: G.list()
> [()]
> sage: G.degree()
> 1
> sage: G = PermutationGroup([[1]])
> sage: G.degree()
> 1
>
> The first group should have degree 0.
>
> 3. Degree 0 should really be supported or
> we will have difficulties with automorphism
> groups of boundary cases. Currently this
> gives an error:
>
> sage: SymmetricGroup(0)
>
> Certainly these examples should go into the
> docstrings.
> Most of these can be trivially fixed, but
> it would be good if someone could review
> permutation groups with a view to catching
> these problems before they arise.
New description:
1. This gives an error:
{{{
sage: G = PermutationGroup([])
sage: G.list()
}}}
2. Permutation group should take an argument for the degree, e.g.:
{{{
sage: G = PermutationGroup([],degree=4)
}}}
3. Permutation group should set the degree correctly:
{{{
sage: G = PermutationGroup([[]])
sage:
sage: G.list()
[()]
sage: G.degree()
1
sage: G = PermutationGroup([[1]])
sage: G.degree()
1
}}}
The first group should have degree 0.
4. Degree 0 should really be supported or
we will have difficulties with automorphism
groups of boundary cases. Currently this
gives an error:
{{{
sage: SymmetricGroup(0)
}}}
Certainly these examples should go into the
docstrings.
Most of these can be trivially fixed, but
it would be good if someone could review
permutation groups with a view to catching
these problems before they arise.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4521#comment:2>
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