#13721: Additional tests for graph symmetries and an improvement of
is_vertex_transitive
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Reporter: azi | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-5.6
Component: graph theory | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Jernej Azarija | Merged in:
Dependencies: | Stopgaps:
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Changes (by boothby):
* status: needs_review => needs_work
Comment:
I haven't tested this, but I've got a couple of comments so far.
1. Edges of graphs can be labeled. The graph
{{{Graph([(0,1,0),(0,1,1)])}}} will be counted as edge-transitive by this
implementation, which is wrong. I recognize the irony of this: the
slapdash code I posted to sage-devel has the same issue. My
recommendation is to add a parameter {{{edge_labels=True}}} because that's
the default 'round these parts. You'll get errors if unhashable edge
labels are used, but that is also true of {{{line_graph}}} so I think this
is acceptable.
2. I'd drop the {{{is_symmetric}}} alias. That's partially motivated by
my dislike for the term (full disclosure). But it's mostly because the
Graph class already has so many methods, we shouldn't frivolously add
aliases.
3. It would be really nice if {{{is_arc_transitive}}} took an extra
parameter so you could check if a graph is (for example) 2-arc transitive.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13721#comment:2>
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