Originally posted by: SystemAdmin

[shadi said:]

i have a model (start with using CP) which i call for each trip, inside this model i have the following constraint:

pay >= 0.9*drivingDistance;

In some trips I have an infeasible problem. when i delete this constraint i have always a soluation,
can i ignore this this constraint when i have an infeasible soluation???

thank you
Kshieboun Shadi



#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

[Didier Vidal said:]

You can write a relaxed version of your model. And for instance, run the relaxed version if your problem doesn't have a solution.

Here is an example:


using CP;

int relaxMode = 1;

dvar boolean enforcement;
dvar int pay;
dvar int drivingDistance;

maximize enforcement;

constraints {

  if (relaxMode == 0)
    enforcement == 1;

enforcement == (pay >= 0.9*drivingDistance) ;
}


Didier.
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

[shadi said:]

Dear Didier,
i really cant understand how i can do this, how i can maximize a boolean variable???
is there an example which i can read??


thank you
Kshieboun Shadi


#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

[Didier Vidal said:]

Hello,

Here are some answers to your questions, which, I hope, will help you understand the model I posted

how i can maximize a boolean variable???

In OPL, a boolean variable has value 0 when false, and 1 when true. Its domain is 0..1 . This is why you can maximize it.
An logical expression (pay >= 0.9*drivingDistance) is considered a boolean expression by OPL (when using CP), with the same convention (0 if false, 1 if true). You can make comparison, sums, product, and any arithmetic operation you want with such expressions. An equality between enforcement, the boolean variable, and a logical expression, means that the enforcement's value is one if and only if the logical expression is true.

Hope this helps.

Didier.
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

[shadi said:]

Dear Didier

i understand now this point...

thank you again...
Kshieboun Shadi
#ConstraintProgramming-General
#DecisionOptimization