Comment by ovolve

Heh. If you look in the code you'll see a big commented out chunk where I tried randomly sampling computer moves to get sort of an 'expected value' for the opposition's move. Empirically, it performed worse. I think this is for the same reason that all minimax algos assume optimal play by the opponent: if you assume optimal and they play less than so, it can only work in your favor. However I think there's some truth in the fact that sometimes an unpredicted random computer move can mess things up. Unfortunately exhaustively enumerating all possible computer moves was way too slow (for single-threaded javascript in the browser).