Originally posted by: SystemAdmin

[cplexuser said:]

Hi,

we used IIS to find the conflicts existing in constraints and bounds for the LP problem we had. I am able to get conficts in constraints with conflict refiner. Is it possible to get the conflicts existing in variables bound along with the conflicts in constraints?

Please suggest.

regards
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Originally posted by: SystemAdmin

[prubin said:]

The feasOpt method allows you to specify both constraint bounds and variable bounds to be relaxed.  The faster modes (minimizing sums of relaxation amounts or sums of squares of relaxation amounts) need not find an irreducible conflict as far as I know.  The MinInf mode will find an IIS, but I'm pretty sure it's solving a MIP to do so, so it can be time-consuming.

AFAIK, the only way to include variable bounds in the conflict refiner is to convert them to constraints.

/Paul

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Originally posted by: SystemAdmin

[cplexuser said:]

Thanks Paul..

Yes, Feasopt always gives constraints and bound conflicts on variables. I checked it and that gives.

CPLEX manual said that we  can solve both constraints and conflicts on bounds of variables with conflict refiner. Infact, interactive optimizer gives both conflicts in constraints and bounds on variables. So wanted to know how we can do that with concert. I can check by converting variable bounds into constraints and see the output.

regards

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#DecisionOptimization

Originally posted by: SystemAdmin

[prubin said:]

Looks like I was half right (or maybe a bit less than half right).  The bounds have to be passed as constraints to the conflict refiner, but apparently they don't have to be constraints in the model formulation.  According the user guide, you can add

IloBound(var[i], IloBound::Lower)

and/or

IloBound(var[i], IloBound::Upper)

to the array of constraints passed in the first argument to refineConflict().
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