Could someone explain this graph ( from Google Deep Mind - Alphazero article) : r/deepmind

AlphaZero - Wikipedia

AI beats AI: AlphaZero becomes the best game player in history

DeepMind's AlphaZero crushes chess

Google AlphaGo Zero masters the game in three days - Queensland

Google Latest AlphaGo AI Program Crushes Its Predecessor

Google Deepmind's AlphaZero Chess Engine Makes Inhuman Knight Sacrifice

Move over AlphaGo: AlphaZero taught itself to play three different games

A general reinforcement learning algorithm that masters chess, shogi, and Go through self-play

DeepMind, Google Brain & World Chess Champion Explore How

PDF] Reproducibility via Crowdsourced Reverse Engineering: A Neural Network Case Study With DeepMind's Alpha Zero