1. The problem statement, all variables and given/known data Create a truth table for ((P->Q) == (Q->P)) 2. Relevant equations 3. The attempt at a solution http://www.freeimagehosting.net/newuploads/94ldj.png I've had two quizes with problems just like this marked wrong in my college logic course. I confronted the professor about it and he just told me to study the truth tables. I'm very confused as to why this is wrong, because I've taken a discreet math course previously.