Hi Bill,
On Sun, Oct 17, 2010 at 12:00 AM, Bill <wode...@iun.edu> wrote:
> When I run
>
> g4=Graph({'H':['G','L','L','D'],'L':['G','D']})
> g4.eulerian_circuit()
>
> I get the error message
>
> Traceback (click to the left of this block for traceback)
> ...
> RuntimeError: Vertex (L) not in the graph.
>
>
> This seems to be an error in the routine.
I think you just discovered that eulerian_circuit() can't handle
multiple edges. If you convert g4 to an undirected graph without
multiple edges, then everything's fine (I hope):
sage: version()
'Sage Version 4.5.3, Release Date: 2010-09-04'
sage: g4 = Graph({'H':['G','L','L','D'], 'L':['G','D']}); g4
Multi-graph on 4 vertices
sage: g4.allow_multiple_edges(False); g4
Graph on 4 vertices
sage: g4.eulerian_circuit(labels=False)
[('H', 'D'), ('D', 'L'), ('L', 'G'), ('G', 'H'), ('H', 'L')]
Thank you for your bug report. This is now ticket #10135:
http://trac.sagemath.org/sage_trac/ticket/10135
--
Regards
Minh Van Nguyen
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