#8404: Computing a H-minor
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Reporter: ncohen | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.3.4
Component: graph theory | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by ncohen):
* status: needs_work => needs_review
Comment:
Hello !!!
Here is a new version of the patch with the examples you requested.
I mever tried to make a mystery that this method is slow. It was one on my
first comments about this patch. The thing is that there is no alternative
that I know of. Minor theory is not what I should work on, but it is an
interesting thing and I tried to find practical algorithms to solve it,
and failed most of the time. I sent messages to people who claimed to have
one and received no answer... And as for every LP algorithm written in
Sage, I consider this one as a quick and lazy way to have some feature
available, and the function as bound to be rewritten as soon as someone
will want to spend time on it.
I would like very much to send a patch soon to be able to compute the
treewidth of a graph, and even heuristics for it.. I would have to ask
this code from a researcher who may be kind enough to share it, but those
would still remain very slow algorithms. I can not stand the very idea of
a heuristic as a mathematician, but sometimes you just have no other
alternative...
As for anonymous reviewing, research has still to learn from Free Software
that we are working together, not competing, and most of the time just
doing the best we can.
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8404#comment:12>
Sage <http://www.sagemath.org>
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