#17132: Perfect Matchings for Graphs
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Reporter: ayyer | Owner:
Type: task | Status: new
Priority: minor | Milestone: sage-6.4
Component: graph theory | Resolution:
Keywords: perfect | Merged in:
matchings, graphs | Reviewers:
Authors: Arvind Ayyer | Work issues:
Report Upstream: N/A | Commit:
Branch: | 88e58625775dfa5cea13db7336dc5f5371ab3768
public/ayyer/perfect_matchings | Stopgaps:
Dependencies: |
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Comment (by ayyer):
> This why the technique is to remove the vertices before calling the
subfunction, and to add them back (with their edges) right after the
subfunction call. This is a way to avoid having many copies of the whole
graph, when all you need is -- as you say -- to have a temporarily smaller
graph.
Oh, I see now! You want me to create another function which will delete
the vertices without creating a copy. Here's what I did, and it seems to
work. It seems a bit long though...
{{{
P = perfect_matchings(Graph([e for e in G.edges() if e[0] != g and e[0] !=
h and e[1] != g and e[1] != h]))
}}}
Is this acceptable? It seems that if {{{G.delete_vertices()}}} returned
the graph instead of removing it in-place, it would have been much easier
to return the graph. I suppose there were good reasons for doing it this
way. Oh well!
Arvind
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Ticket URL: <http://trac.sagemath.org/ticket/17132#comment:27>
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