#9911: Changing the LP formulation of feedback vertex/arc set to improve the
speed
----------------------------+-----------------------------------------------
Reporter: ncohen | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-4.6.1
Component: graph theory | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by abmasse):
* status: needs_review => needs_info
Comment:
Hi Nathann !
A question and a remark:
1. If I understand correctly, your ticket is improving the speed of the
minimum feedback vertex/arc set problems by providing another LP
formulation. Could you detail where you took the first formulation (I
assume you're the one who coded it) and where you got the new one? This
could help in the review process to compare and make sure the two methods
are equivalent.
1. I a bunch of lines where lists are created without being used, such
as in:
{{{
[p.add_constraint(d[v],min=n) for v in self]
}}}
Wouldn't it be better to replace it with a loop?
{{{
for v in self: p.add_constraint(d[v], min=n)
}}}
I think it's useless to create a list that will be thrown to the garbage
collector right away :) Moreover, the number of characters is exactly the
same, so it's not a waste of space :)
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9911#comment:5>
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