This function creates and returns a constraint (an instance of IloConstraint) for use in a model. That constraint forces var1 to be strictly a subset of var2. That is, there is at least one element of var2 not in var1, and all elements of var1 are in 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.