Oliver Roeder: The Guessing Game

Chip in. Lay your cards on the table. Go all-in. The English language is peppered with poker terms. Such is the popularity of the game that even non-players know what is meant by these idioms. With the rise of online poker, it is no longer the exclusive domain of high-flying players; anyone with an internet connection can instantly play for money. Unless you are a professional player, however, the odds are you will lose more money than you win. So, what is it about poker that is so appealing?

POKER FACE

For some, it is the psychology. For others, it is the lure of money. According to the book Poker for Dummies, “the objective of poker is to win money by capturing the pot, which contains bets made by various players during the hand.” Bets are made by players according to ‘their hand’ (that is, the cards they hold.) If they think they have a strong hand, they try to convince their opponents to ‘fold’ or abandon their cards. They can also pretend to have a strong hand, even if they do not, as a bluff, intimidating the other players into folding. The best players can do this very convincingly, their face expressionless or exuding confidence. This is what is called a ‘poker face’.

GAME THEORY

In the language of game theory, poker is a game of imperfect information. None of the players know which cards are held by the others. A big part of the strategy is working out what cards they have in their hands. Such a skill is useful in real-life situations like negotiations, dating or even war, so poker attracts people from all walks of life.

Despite imperfect information, artificial intelligence has evolved to such an extent that it has optimised game play. In 2016, DeepStack became the first AI capable of beating professional poker players at ‘heads-up, no-limit Texas Hold’em’.

TEXAS STYLE

Texas Hold’em is the most well-known variation of poker. There are three main categories: draw games, stud games and community card games. Texas Hold’em belongs to the latter. Heads-up games involve two players and no-limit poker means there is no limit to the size of the bets that can be placed. Today’s AIs are so good, they usually beat humans in any kind of poker. They are therefore used by players to train and improve their game. They know that, when the chips are down, poker apps can help them play the hand they’ve been dealt!