#8425: BipartiteGraph add_edge allows bipartite property to be violated.
----------------------------+-----------------------------------------------
Reporter: rhinton | Owner: rhinton
Type: defect | Status: new
Priority: major | Milestone: sage-4.3.4
Component: graph theory | Keywords: BipartiteGraph, add_edge
Author: Ryan Hinton | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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add_edge() needs to be overridden in !BipartiteGraph in order to preserve
the bipartite property of the graph.
{{{
sage: # non-bipartite graphs are rejected by the constructor
sage: BipartiteGraph(Graph({0:[1,2], 1:[2]}))
Traceback (most recent call last)
...
TypeError: Input graph is not bipartite!
sage: # but the same graph can be constructed edge-by-edge without raising
an error
sage: bg = BipartiteGraph()
sage: bg.add_vertices([0,1,2], left=[True,False,True])
sage: bg.add_edges([(0,1), (1,2)]) # good so far
sage: bg.add_edge(2,0) # should raise exception!
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8425>
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