#18871: MILP formulation for cutwidth
-------------------------+-------------------------------------------------
Reporter: | Owner:
dcoudert | Status: needs_review
Type: | Milestone: sage-6.8
enhancement | Resolution:
Priority: major | Merged in:
Component: graph | Reviewers: Nathann Cohen
theory | Work issues:
Keywords: | Commit:
cutwidth, MILP | 1004fb864b661f6d79fbb225062528b06b2081aa
Authors: David | Stopgaps:
Coudert |
Report Upstream: N/A |
Branch: |
public/18871 |
Dependencies: |
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Changes (by ncohen):
* status: needs_work => needs_review
Comment:
Hello again,
I added a small commit with a couple of modifications:
- replaces "A - B <= 0" constraints with "A <= B"
- Removed 'except:'
The problem with 'except' without any exception name is that it catches
too much:
{{{
sage: try:
....: p.solveeeeee()
....: except:
....: raise ValueError("Infeasible Problem")
ValueError: Infeasible Problem
}}}
This way, the LP solver is forwarded to the user, and it will be more
meaningful that a generic error message: on my computer I get this:
{{{
sage: cutwidth.cutwidth_MILP(G, lower_bound=G.size()+1)
...
MIPSolverException: 'CPLEX: The primal has no feasible solution'
}}}
You can change the ticket's status to `positive_review` unless there is
something that you want to change.
Have fuuuuuuun,
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/18871#comment:8>
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