A and B are each either a knight or a liar. A says, "At least one of us is a liar." What are A and B?
If A is a liar, then it he/she is telling the truth, contradicting his/her being a liar. Thus A is a knight. If A is a knight, the the statement is true and at least one of A and B are a liar. Since A is not a liar, that means B is. Thus A is a knight and B is a liar. All of this of course assumes that Math Man is himself a knight :).

Posted by Daniel
on 20130411 09:55:22 