 After four hours of training, DeepMind estimated AlphaZero was playing at a higher Elo rating than Stockfish 8; after 9 hours of training, the algorithm defeated Stockfish 8 in a time-controlled 100-game tournament (28 wins, 0 losses, and 72 draws).The trained algorithm played on a single machine with four TPUs.DeepMind's paper on AlphaZero was published in the journal "Science" on 7 December 2018.