For details, see A general reinforcement learning algorithm that masters chess, shogi, and Go through self-play | Science
"DeepMind, the London-based subsidiary of Alphabet, has created a system that can quickly master any game in the class that includes chess, Go, and Shogi, and do so without human guidance.DeepMind Achieves Holy Grail: An AI That Can Master Games Like Chess and Go Without Human Help | IEEE Spectrum
The system, called AlphaZero, began its life last year by beating a DeepMind system that had been specialized just for Go. That earlier system had itself made history by beating one of the world’s best Go players, but it needed human help to get through a months-long course of improvement. AlphaZero trained itself—in just 3 days."