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To Mock a Mockingbird

en.wikipedia.org/wiki/To_Mock_a_Mockingbird

To Mock a Mockingbird and Other Logic Puzzles: Including an Amazing Adventure in Combinatory Logic is a book by the mathematician and logician Raymond Smullyan. It contains many nontrivial recreational puzzles of the sort for which Smullyan is well known. It is also a gentle and humorous introduction to combinatory logic and the associated metamathematics, built on an elaborate ornithological metaphor.