Originally posted by: UmarWaqas

Hi, I am trying to implement an OPL model which reads the names from a set and populates an array. The constraints have to be specified on the populated array.
The population is performed in pre-processing (ILOG OPL script). Please consider the code below:

/**************************/
{string} names = {"Mike","Tim"};
int members;
string populatedhttp://1..members;

execute INITIALIZE {

members = 2;
var count = 1;
for (var i in names)
{
populatedcount = i;
count++;
}
}

/* Decision variables */
dvar int dummyhttp://1..members in 1..10;
subject to{

forall (i in 1..members)
{
/* Required: this statement just checks whether "Mike" is accessed through "populated" */
(populated[i] == "Mike") => (dummy[i] != 2);
}
}

/**************************/

The compiler reports following errors:
1) CPLEX(default) cannot extract model: IloAlgorithm cannot extract extractable.
2) CPLEX(default) cannot extract expression: populated[i] == "Mike".
3) CPLEX(default) cannot extract expression: forall(i in 1..2) populated[i] == "Mike" => dummy[i] != 2.

I think i am misunderstanding the programming constructs available. Please rectify if possible.
#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

In an OPL model, constraints are stated on variables. Integers varaiables are declared like this :

dvar int x in 1..1000;

They need to have a integer range of values as a domain.

In your model, populated is not an array of variables and the string "Mike" canot be a domain value, thus the errors. Note that if your intend is to use constraint programming for solving this model, you need to add

using CP;

at the top of the model.
#ConstraintProgramming-General
#DecisionOptimization