Tic-tac-toe is proven to be unlosable. (You can win if you go first & you are playing an imperfect opponent) Check out http://en.wikipedia.org/wiki/Tic-tac-toe

Tic-tac-toe is proven to be unlosable. (You can win if you go first & you are playing an imperfect opponent) Check out http://en.wikipedia.org/wiki/Tic-tac-toe#Strategy http://en.wikipedia.org/wiki/Tic-tac-toe#Strategy for the description of the algorithm.