Lee Sedol, seated at right, one of the greatest modern players of the ancient game of Go, was defeated three times in a row by Google’s DeepMind supercomputer, AlphaGo. Experts had long suggested that Go was a game in which computers would struggle to match human intellect. (Illustration: Joseph M. Gerace/NJ Advance Media; Photo: Google DeepMind/Agence France-Presse)