[Coin-discuss] How to cut off "optimal" solution in CBC

[Michael Hennebry]

As I understand the problem, the scenario to be avoided is:

Cbc is fed an insufficient set of constraints.

Cbc finds an integer solution to that
set and incorrectly (from the users
point of view) deems it the incumbent.

Cbc invokes a cut generator that finds
a cut violated by the incumbent.


I don't know that the problem is rare.
It occurs in a common formulation of the TSP.


If Cbc has a callback to test feasibility,
the user should use that.
If not, adding one would not seem difficult.
An explicit test for feasibility would seem the ideal.

Note that if an all-integer solution is
declared infeasible and no cut is generated
Cbc would have no way to proceed.

Possibly more complex would be to
modify Cbc to invoke the cut generator
before testing for feasibility.
If a violated cut is generated,
the current solution is not feasible.

-- 
Mike   hennebry at web.cs.ndsu.NoDak.edu
"There are three kinds of people,
those who can count and those who can't."