Pluribus is a
computer poker player
A computer poker player is a computer program designed to play the game of poker against human opponents or other computer opponents. It is commonly referred to as pokerbot or just simply bot.
On the Internet
These bots or computer programs ar ...
using
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech ...
built by
Facebook's AI Lab and
Carnegie Mellon University
Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania. One of its predecessors was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools; it became the Carnegie Institute of Technology ...
. Pluribus plays the
poker
Poker is a family of comparing card games in which players wager over which hand is best according to that specific game's rules. It is played worldwide, however in some places the rules may vary. While the earliest known form of the game wa ...
variation no-limit
Texas hold 'em
Texas hold 'em (also known as Texas holdem, hold 'em, and holdem) is one of the most popular variants of the card game of poker. Two cards, known as hole cards, are dealt face down to each player, and then five community cards are dealt fa ...
and is "the first bot to beat humans in a complex multiplayer competition".
According to the Pluribus creators, "Developing a superhuman AI for multiplayer poker was the widely recognized main remaining milestone" in computer poker prior to Pluribus. Pluribus relies on offline self-play to build a base strategy, but then continues to learn in real-time during its online play. The base strategy was computed in eight days, and at market rates would cost about $144 to produce, much smaller than contemporary superhuman game-playing milestones such as
AlphaZero
AlphaZero is a computer program developed by artificial intelligence research company DeepMind to master the games of chess, shogi and go. This algorithm uses an approach similar to AlphaGo Zero.
On December 5, 2017, the DeepMind team re ...
. In AI, two-player zero-sum games (such as heads-up hold'em) are usually won by approximating a Nash equilibrium strategy; however, this approach does not work for games with three or more players. Pluribus instead uses an approach which lacks strong theoretical guarantees, but nevertheless appears to work well empirically at defeating human players. Across the competitions, Pluribus won an average of over 30 milli big blinds per game. Pluribus' self-learned play style avoids "limping" (calling the big blind), and engages in "donk betting" (ending a round with a call and starting the next round by betting) more often than human experts do.
Among expert poker players, Jason Les stated he felt "very hopeless. You don't feel like there’s anything you can do to win."
Chris Ferguson
Christopher Philip Ferguson (born April 11, 1963) is an American professional poker player. He has won six World Series of Poker events, including the 2000 WSOP Main Event, and the 2008 NBC National Heads-Up Poker Championship. Ferguson is a ...
stated "Pluribus is a very hard opponent to play against. It's really hard to pin him down on any kind of hand." Jimmy Chou stated "Whenever playing the bot, I feel like I pick up something new to incorporate into my game." In ''
The Wall Street Journal
''The Wall Street Journal'' is an American business-focused, international daily newspaper based in New York City, with international editions also available in Chinese and Japanese. The ''Journal'', along with its Asian editions, is published ...
'', science editor Daniela Hernandez characterized Pluribus as "advanced at a key human skill — deception".
Following the victory, the developers declined to release the source code, out of fear it would be misused to surreptitiously cheat against human poker players in online matches.
References
{{Reflist
Computer poker players