Libratus beats poker professionals
In January 2017 Carnegie Mellon University's Libratus played 120,000 hands of heads-up no-limit Texas hold'em over twenty days against four professionals at Rivers Casino in Pittsburgh, and finished on 30 January ahead by $1,766,250 in chips.
Why it matters
By its authors' account this was the first win of a program over the strongest humans at a large game of imperfect information, where the opponent hides cards and bluffs. Chess and Go, where Deep Blue and AlphaGo had won, are games of perfect information; here the strategy had to be computed without knowing the other hand.
Noam Brown and Tuomas Sandholm's paper in Science (online 17 December 2017) gives a margin of 147 thousandths of a big blind per hand and p = 0.0002 if the hands are treated as independent; Libratus also beat each of the four players individually. The strategy was computed on the Pittsburgh Supercomputing Center's Bridges before and during the match. A $200,000 prize pool was split among the humans by result, with $20,000 guaranteed to each. The record does not claim a start day: the release and the paper say only twenty days and January 2017; nor does it claim 14.7 big blinds per hundred hands, which occurs in neither source read.