Artificial intelligence (AI) programs have bested humans in checkers, chess, go and two-player poker, but multiplayer poker was always believed to be a bigger ask. Researchers at Carnegie Mellon University, working with Facebook's AI initiative, on Thursday announced that their program defeated a group of top professionals in six-player no-limit Texas Hold'em. The program, Pluribus, and its big wins were described in the US journal Science. "Pluribus achieved superhuman performance at multiplayer poker, which is a recognized milestone in artificial intelligence and in game theory," Carnegie Mellon computer science professor Tuomas Sandholm said. Sandholm worked with Noam Brown, who is working at Facebook AI while completing his doctorate at the Pittsburgh-based university.