Cepheus learned poker by playing over a billion billion hands – more than have been played in the entirety of human history.
It may not win every hand it is dealt, but over time, no one can beat Cepheus, a computer program that scientists claim plays a near-perfect game of poker.
Unveiled in Canada on Thursday, the researchers believe that Cepheus is so good that a seasoned poker star could spend their whole life playing against it and still not come out on top.
To learn the game, Cepheus spent two months playing the equivalent of more than a billion billion hands of Texas hold’em, which is more poker games than have been played in the entirety of human history.
The feat required the number-crunching power of four thousand computer processors, each handling six billion hands every second. With each game Cepheus played, the program built up a database of cards dealt, betting decisions and outcomes. At the end of the marathon training session, the database contained 11 terabytes of information on calls, raises and folds for every hand a player could have.
Cepheus learns from an algorithm that essentially minimises its regrets: the program reviews every decision made and then learns which moves paid off and which cost it the hand. “For every single possible situation you could get into, it has a description for how you should play,” said Neil Burch, a computer scientist who helped develop Cepheus at the University of Alberta Computer Poker Research Group.
The program plays a variant of poker called heads-up limit hold’em, made famous by Michael Craig’s 2005 book, The Professor, the Banker and the Suicide King. The game involves two players who bet fixed amounts with a limit on the number of raises allowed.