Hi! I've problem proving a logical statement. I really can nothing about logic. I just messing around with some in a try to prove another theorem. Anyway, I would be useful to be able to prove that: ([itex]P_b[/itex] and not [itex]P_1[/itex]) and ([itex]P_b[/tex] and not [itex]P_2[/tex] and ... as P1, P2, P3 ... equals Pb and not (P1, P2, P3 ...) I don't know if this is the proper way to express this, but I hope you will get my point. If not ask. And please correct me.