Originally posted by: qtbgo

Hi, in the following constraint, x[i] is bool var. S is a set, I use script to change S dynamicly. Now, in my procedure, sometimes S will be set as an empty set, then the constraint will be reported infeasible (0>=1), this is not what I want. I want that when S is empty, the constraint should be ignored simply. Could someone help me to resolve this problem?   Sorry for my poor English, hope you can understand.

  sum(i in S)(1-x[i])>=1

Hi,

could

{int} S={};
dvar int x[1..10] in 1..10;

subject to
{

if (card(S)>=1) sum(i in S)(1-x[i])>=1 ;

}

help ?

regards

Originally posted by: qtbgo

thank you.

card(S)*sum(i in S)(1-x[i])>=1*card(S)