Hold 'Em or Fold 'Em? This A.I. Bluffs With the Best

As Mr. Elias realized, Pluribus knew when to bluff, when to call someone else's bluff and when to vary its behavior so that other players couldn't pinpoint its strategy. "It does all the things the best players in the world do," said Mr. Elias, 32, who has won a record four titles on the World Poker Tour. "And it does a few things humans have a hard time doing." Experts believe the techniques that drive this and similar systems could be used in Wall Street trading, auctions, political negotiations and cybersecurity, activities that, like poker, involve hidden information. "You don't always know the state of the real world," said Noam Brown, the Facebook researcher who oversaw the Pluribus project.