Smullyan was one of the greats.
I used to have one of his puzzle books, probably it’s still somewhere at my parent’s place. I liked it. I am not so much familiar with his other work and life though.
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Aside from his puzzles (which I adored), he wrote great books on math problems and theorems, and some pop philosophy that I really enjoyed. And lived into his '90s, so we got a lot from him.
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