bug in SymmetricGroup(1).cayley_graph()

[sagetrac-mabshoff]

In https://groups.google.com/group/sage-support/browse_thread/thread/443ce49730b43396 M. Fix reported:

Hello-
I input the following:

sage: s1 = SymmetricGroup(1)
sage: s = s1.cayley_graph()
sage: s.vertices()
[]

Shouldn't the set of vertices have one element in it for the
identity?  s1 reports this element, but as shown the graph does not.
I suppose this is trivial, but it seems like it should be fixed at
some point.  I am, however, still fairly new to SAGE, and could easily
be missing something.  Any thoughts on this? 

Cheers,

Michael

Component: graph theory

Issue created by migration from https://trac.sagemath.org/ticket/3070

[rlmill]

Attachment: trac3070-cayley_graph_constructor.patch.gz

[rlmill]

comment:1

Applied to sage-3.0 on my macbook:

$ ./sage -t devel/sage/sage/groups/
... 
----------------------------------------------------------------------
All tests passed!
Total time for all tests: 178.3 seconds
$ ./sage -t devel/sage/sage/graphs
...
----------------------------------------------------------------------
All tests passed!
Total time for all tests: 217.6 seconds

[rlmill]

comment:2

Conclusion:

The function cayley_graph was unnecessarily complicated.

[jasongrout]

comment:3

the patch looks good to me. I didn't apply or doctest it, though.

[sagetrac-mabshoff]

comment:5

Doctests pass with the patch applied.

Cheers,

Michael

[sagetrac-mabshoff]

comment:6

Merged in Sage 3.0.1.rc0