Truth Table for "A unless B", or "A , only if B"? Hi, All: My friend is preparing for the LSAT's, and he asked me to help her with the Logic Games part. Two of the binary connectives often used in those games are 'unless', and 'only if'. I guess I'm being kind of lazy , hoping someone has already run into these two. I assume both of these connectives are true exactly when both inputs are true or both inputs are false, as in: " I don't sleep unless I'm tired", or "I sleep only of I'm tired". Then, it would seem. Is this a correct description? Thanks.