1. The problem statement, all variables and given/known data I am trying to prove (~P & ~Q) => ~(P V Q) using only MP, negation elimination, &I conjunction, &E simplification, addition, constructive dilemma, biconditional introduction and elimination, conditional proof, and reductio ad absurdum. 2. Relevant equations 3. The attempt at a solution It seems to me that the only way to do the prove is reductio ad absurdum. But, I am stuck after hypothesizing (P V Q). I looked at embedding other hypothesis to get a useful negation but could only come up with ~(P & Q). I don't think it will be useful. Any hints on the hypothesis I need to use?