Hi,

let 's start from https://www.ibm.com/developerworks/community/forums/html/topic?id=9748cb9c-fa58-471a-8f9b-fba546df609b&ps=25

Now let's see how easy it is to write if then else constraints :

int nbKids=300;
float costBus40=500;
float costBus30=400;

 
dvar int+ nbBus40;
dvar int+ nbBus30;

minimize
 costBus40*nbBus40  +nbBus30*costBus30;
 
subject to
{
 40*nbBus40+nbBus30*30>=nbKids;
 
 // with if nb buses 40 more than 3  then nb buses30 more than 7
 
 (nbBus40>=3)=>(nbBus30>=7);
 //(nbBus40>=3)<=(nbBus30>=7); //equivalent
}
 

which gives

nbBus40 = 0;
nbBus30 = 10;

PS: Many other simple examples at https://www.linkedin.com/pulse/making-decision-optimization-simple-alex-fleischer/