optimizationmodelcplexopl

Why is my OPL model not providing a solution for the evacuation problem?

I'm working on an OPL model for a two-floor evacuation simulation. The model is supposed to calculate the flow of people evacuating from various nodes to the exits while considering constraints like capacity and travel time. However, I'm encountering issues where the model fails to provide any solutions.

Expected Outcome I expect the model to calculate the flow of people from the starting nodes to the exits (E1 and E2) within the defined time horizon while respecting all the constraints. Instead, it returns no feasible solutions, and the solver outputs show minimal processing time without indicating any progress.

Solution

  • your model may be infeasible. If you name your constraints you could get some relaxation / conflict.

    For instance

    int nbKids=300;
float costBus40=500;
float costBus30=400;
 
dvar int+ nbBus40;
dvar int+ nbBus30;
 
minimize
 costBus40*nbBus40  +nbBus30*costBus30;
 
subject to
{
 ctAllKidsNeedToGo:
     40*nbBus40+nbBus30*30>=nbKids;
 
 ctMaxTotalBuses:
     nbBus30+nbBus40<=7;
}

    will display conflict and relaxation in the IDE

    relaxation

    https://github.com/AlexFleischerParis/zooopl/blob/master/zooconflictandrelaxation.mod