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javaconstraint-programmingchoco
JackAW
JackAW

Reputation: 173

Constraint in Choco

I've found a Choco solver as constraint programming software working with Java. I would like to learn it more. I have done some basic example. But now I would like to try something more complex (Pritsker project scheduling alg) and I need your help. In order to progress I have to understand how to put constraints on rows of matrix variable. Exactly I need to keep a sum of rows equal 1 (task starts only once). I have tried it but unsuccessfuly. Could you help? I do use Choco 2.1.5 My matrix is as follows:

int n = 10; // projects
int m = 12; // time horizon in months
IntegerVariable[][] x = new IntegerVariable[n][m];
int i, j;
for (i = 0; i < n; i++){
    for (j = 0; j < m; j++){
        x[i][j] = Choco.makeIntVar("x_" + i +"_" + j, 0, 1, Options.V_ENUM);
        model.addVariable(x[i][j]);
    }
}

Upvotes: 0

Views: 1675

Answers (2)

Virgile BRIAN
Virgile BRIAN

Reputation: 33

To add constraint over the rows, you should transpose the matrix and apply the constraint over the lines :

transposed = ArrayUtils.transpose(x);
for(int i=0; i<n; ++i){
    model.sum(transposed[i], "=", 1);
}

Upvotes: 0

padawan
padawan

Reputation: 1315

You should define variables as rows and columns first.

Than, you may use this documentation to proceed. Something like this might be helpful:

IntegerVariable[][] rows;
int n; //number of rows
for(int i=0; i<n; i++)
   model.addConstraint(eq(sum(rows[i], 1));

Upvotes: 1

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