public BDD support() { BDD r1 = b1.support(); BDD r2 = b2.support(); return new TestBDD(r1, r2);
public BDDVarSet support() { BDDVarSet r1 = b1.support(); BDDVarSet r2 = b2.support(); return new TestBDDVarSet(r1, r2);
        public BDD support() {            BDD r1 = b1.support();            BDD r2 = b2.support();            return new TestBDD(r1, r2);        }