Intersections

Set intersections can be formed using a multiplication type operation namely (setarith.gms)

Subset3(superset) = Subset1(superset) * Subset2(superset);

The membership of subset3 contains all elements that are members of both subset1 and subset2.  This operation is equivalent to the statements

Subset3(superset)=yes$(subset1(superset) and subset2(superset));