[mzer]

I haven't studied logic in 25 years, and while I seem to remember more than I would imagine I would, one simple proof is escaping me. In fact, it seems I remember the more complex issues better than the simple ones.

In trying to assist my nephew with a problem, I have become stumped. Obviously, the relationship is obvious intuitively, but I am having some odd problem with the conversion. If somebody could show me the proof for this, I would be most thankful:

A iff B is equivalent to (A and B) or (not A and not B).