#12716: MILP formulation and test functions for vertex separation
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Reporter: dcoudert |
Owner: jason, ncohen, rlm
Type: enhancement |
Status: needs_work
Priority: major |
Milestone: sage-5.0
Component: graph theory |
Resolution:
Keywords: graph, decomposition, linear ordering, pathwidth | Work
issues:
Report Upstream: N/A |
Reviewers: Nathann Cohen
Authors: David Coudert |
Merged in:
Dependencies: |
Stopgaps:
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Changes (by ncohen):
* status: needs_review => needs_work
Comment:
Helloooooooooo David !!!
Here is a small patch to apply on top of yours.. Here is what it does :
* One or two typoes
* Simplifies the definition of the LP variables... Could you give it a
look, just to check I got nothing wrong ? `:-)`
* Replaces some lists operation by set operations. Well, it looked
like all you wanted to do was more a set thing than a list thing.
* Replaces some integer = True by binary = True. The solvers (well,
except Coin as usual) have specific types for binary variables, so if we
know that they are binary we may as well say it.
* I also moved several lines of code outside of the try/catch, as list
operations usually do not throw MIPSolverExceptions
I also have several questions :
* Could you say in the doc which variables are relaxed when
integrality=False, and if it has any specific meaning ? Or is it just a
lower bound that you use because it is faster ?
* Is the integrality variable really intended to be False **by
default** ? `O_o;;;`
* About constraints 5, 6, and 7 : why aren't they all set by "sum of
all y[v][t] for all v is equal to t" ? Or rather to t+1 ? I do not get why
you do not say so immediately to the solver `O_o`
* To me ``u[v][t] >= x[v][t]-y[v][t]`` is rather ``x[v][t] == u[v][t]
+ y[v][t]``, which is the same constraint but in a way I find easier to
read.. That's one of the remarks I added to the definition of the
variables, though `:-)`
Well, I think that's all I had to say !
Nathann
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12716#comment:4>
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