Up to equivalence, there aren’t nine distinct opening moves. There are only three. If it isn’t immediately clear to you what “up to equivalence” means here, I urge you to try and figure it out ...

[Nicholas Carlini] programmed a C implementation of two-player Tic Tac Toe, and he did it in a single call to printf(). The arguments for that single function call get mind-bendingly complex, so it ...