#4445: is_isomorphic throws an error when the graph is compared to itself
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Reporter: jason | Owner: rlm
Type: defect | Status: new
Priority: major | Milestone: sage-3.2
Component: graph theory | Keywords:
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Consider:
{{{
sage: g=graphs.HeawoodGraph()
sage: g.is_isomorphic(g)
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/jason/<ipython console> in <module>()
/home/jason/sage/local/lib/python2.5/site-packages/sage/graphs/graph.pyc
in is_isomorphic(self, other, certify, verbosity, edge_labels)
6540 G2 = other; partition2 = [other.vertices()]
6541 from sage.misc.flatten import flatten
-> 6542 isom = isomorphic(G, G2, partition, flatten(partition2,
max_level=1), (self._directed or self.loops()), 1)
6543 if not isom and certify:
6544 return False, None
/home/jason/sage/local/lib/python2.5/site-
packages/sage/groups/perm_gps/partn_ref/refinement_graphs.so in
sage.groups.perm_gps.partn_ref.refinement_graphs.isomorphic
(sage/groups/perm_gps/partn_ref/refinement_graphs.c:9946)()
TypeError: 'NoneType' object is unsubscriptable
}}}
However,
{{{
sage: g.is_isomorphic(graphs.HeawoodGraph())
True
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4445>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
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