From here on, use simplification and disjunctive syllogism in the
restricted sense. Simplify only from the left side, and in disjunctive
syllogism, derive the right disjunct by denying the left disjunct.

       I.   Complete the following derivations:

           A.   Derive ~(P & Q) from

               1.   ~P <-> Q                Premise

           B.   Derive P v Q from

               1.   P v (P v Q)             Premise

           C.   Derive P <-> Q from

               1.   ~(~P v ~Q)              Premise

           D.   Derive P from

               1.   P <-> Q                 Premise
               2.   Q                       Premise

           E.   Without using MT, derive ~P from

               1.   P -> Q                  Premise
               2.   ~Q                      Premise