How AlphaZero Works

Recently I posted about the phenomenal performance of the AlphaZero algorithm in computer chess. For the first time in history, an algorithm displayed human-like understanding of chess. AlphaZero seemed to understand what moves were best and spent its time focusing only on them. It didn't mechanically crunch through millions of possible positions, run out of time, and then select the best move. The best moves emerged from its computer neural network, like a human grandmaster. It was given just the rules of chess and nine hours to play itself 44 million games, and then it learned something so deep about chess that it crushed the world champion computer chess program, Stockfish, 155 games to 6. (They played 1,000 total games; at this level most games are draws.)