This function creates and returns a constraint (an instance of IloConstraint) for use in a model. That constraint forces var1 to be a subset of var2. (The set var1 may be equal to var2; every element of var1 is also an element of var2.)

In order for the constraint to take effect, you must add it to a model with the template IloAdd or the member function IloModel::add and extract the model for an algorithm with the member function IloAlgorithm::extract.