1. The problem statement, all variables and given/known data I don't have symbols for negations, so i'll just use the word NOT.. Prove the validity of the sequents below: NOT ( P -> Q) YIELDS Q-> P 2. Relevant equations Relavent deductions as listed here.. http://en.wikipedia.org/wiki/Propositional_logic Using things such as ^ elimination/introduction, Modens Ponens,.. etc 3. The attempt at a solution 1. NOT ( P -> Q) Premise ___ 2. NOT Q Assumption 3. NOT NOT P MT 1,2 (added in extra negation from line 1) 4. P NOT NOT Elimination ____ 5. NOT Q -> P I"m looking for Q -> P.. which the opposite answer.. i think its something to do with the negations being all wrong.. any help??