Originally posted by: SystemAdmin

[Sylvain said:]

Is it possible to simultaneously schedule filling and emptying activities on an IloContinuousReservoir ?
My experiments seem to show that the solver fails in these cases.
Is that a normal behaviour ?

#ConstraintProgramming-General
#DecisionOptimization

Originally posted by: SystemAdmin

[Sylvain said:]

I found the origin of my problem.
There seem to be a bug in the implementation of precedence graphs for continuous reservoirs.

Consider the following simple program :

IloModel model(env);

IloContinuousReservoir res(env, 100);
res.setInitialLevel(50);

IloActivity act1(env, 1);
IloActivity act2(env, 1);
model.add(act1.startsAt(0));
model.add(act2.startsAt(0));

model.add(act1.consumes(res, 200));
model.add(act2.produces(res, 200));

IloSolver solver(model);
IlcScheduler scheduler(solver);

res.setPrecedenceEnforcement(IloBasic);

if(solver.solve(IloGoalTrue(env)))
cout << "Feasible" << endl;<br /> else
cout << "Infeasible" << endl;<br />
res.setPrecedenceEnforcement(IloMediumHigh);

if(solver.solve(IloGoalTrue(env)))
cout << "Feasible" << endl;<br /> else
cout << "Infeasible" << endl;<br />

The results is :
Feasible
Infeasible

With a precedence enforcement greater than IloMediumHigh, the precedence graph constraint is posted and makes the solver fail with no reason.

This should be corrected in future releases...
#ConstraintProgramming-General
#DecisionOptimization