#7364: Eulerian orientation of a graph
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Reporter: ncohen | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.3
Component: graph theory | Keywords:
Work_issues: | Author:
Upstream: N/A | Reviewer: Florent Hivert
Merged: |
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Comment(by ncohen):
To Robert : Thank you very much !!!! I'll definitely give it a look ! But
you make it sound like I would then have to work on a new graph rather
than use the Python one ! In this case, I do not really need to create a
new graph but I would like the functions "get an edge coming out of this
vertex" and "tell me where it goes" to be extremely fast... When will the
default Sage Graph the be C ones ?
To Florent : I'm aware this only means changing a "factor", but I am
living among computer scientists who find it extremely hard to stop
thinking like "it is NP-complete : there is no algooorithm to solve it".
And I swear I did not forget the word "polynomial". At some point I also
wanted to write an algorithm ion Sage to compute the crossign number of a
graph. Bruce Reed published a Linear Time algorithm for this problem,
using Graph Minor theory. The result is a (2^2^2^2^2^2^2^2.... ) * n
algorithm which no one can implement, even less use. That's why I prefer
mentionning the "two". Besides, one of the reasons people in my lab keep
from really switching to Sage is that they currently use Java, which is
way faster. ( of course they have less algorithms, of course they miss
many things, but Still, it is faster )
I'll update this patch today !
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7364#comment:11>
Sage <http://www.sagemath.org>
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