Puzzles from Raymond Smullyan
"Professor Smullyan was a serious mathematician, with the publications and the doctorate to prove it. But his greatest legacy may be the devilishly clever logic puzzles that he devised, presenting them in numerous books or just in casual conversation."
One of my friend drew my attention to this article on NY Times.
The article contains 5 of his puzzles.
R.I.P Raymond Smullyan [02/06/17]