Smullyan ... sounds like a Tolkien character name, but it is not. Raymond
Sully was mathematical logic (and curiously Taoist). He has several books of logic puzzles. Two things I want to leave here written on ...
1) The hardest logical puzzle there is:
"Three gods A, B, C are called (in some order) Truth, Lies and Azar. Truth always speaks the truth, but lie always lie about Azar ... everything is just luck. Your task is to determine identities formulating three questions (the answers should be YES or NO). Every question must be made to a single God (rather than several at once). All three understand your language, but will respond in a language you do not know. Only I can tell you in that language will say YES and NO DA or JA (but do not know which is which). "
Notes:
*) You can do all three questions to the same god, one or two questions and one question to another, or a question to everyone, etc ....
*) The two questions three may depend on previous responses.
2) A fictional dialogue (but interesting) of a mortal and God.
http://www.mit.edu/people/dpolicar/writing/prose/text/godTaoist.html
initiated at the request of a person to God to take away the "free will."