Google's parent company Alphabet-owned artificial intelligence (AI) firm DeepMind has revealed that its computer programme 'AlphaZero' learned chess rules in four hours. It also revealed that AlphaZero mastered the game enough to defeat the world's strongest open-source chess engine, Stockfish. Last year, DeepMind's programme AlphaGo beat Chinese game 'Go' champion Lee Sedol in a five-game match.