The Jacoby Rule

Those who venture into the exciting world of backgammon, and in particular when playing for money may hear of the Jacoby rule being applied during a game. This rule cancels the point values of a gammon and backgammon for a game if the game has not been doubled. To understand the Jacoby rule you must first be familiar with doubling. Doubling is a strategy in backgammon whereby players challenge each other to accept doubling the stakes of the game, or resign. In practice this is done using the doubling cube which is an additional dice marked with the numbers 2, 4, 8, 16, 32, and 64. Doubling is used in matches when a player wants to take advantage of a strong position in a game to pull ahead on points or alternatively by a trailing player hoping to make up for lost games.

When playing for money the doubling cube can raise the stakes of a single game to significantly more than the original wager on the game. However, when playing a series of games for money, players can sometimes become hesitant about doubling the game because they hope to rely on getting a gammon or backgammon to edge them closer to a final victory. This can drag out some games where the victor is already clear from his or her stronger position. This is where the Jacoby rule comes in. First proposed by one of the greatest bridge players of all time, Oswald Jacoby, the Jacoby rules states that gammon and backgammon points are only counted for their double and triple points if the game has already been doubled. The idea behind the rule is to prompt leading players to finish a match off quickly by doubling a game rather then taking a slow steady pace. Without the incentive of gammon or backgammons players are more likely to double up the game when they feel they are heading for a win.

So Who was Oswald Jacoby and Why was He in Such a Hurry?

Oswald Jacoby was born in Brooklyn in 1902. He first learnt to play when he was just six years old. During World War I he lied about his age and joined the army at the age of just fifteen where he spent a lot of time playing poker. His brilliance for statistics became apparent when at 21 he became the youngest person to pass the Society of Actuaries exam. However it was in playing bridge that Jacoby gained international fame both as a columnist and an expert player. Jacoby published many books on bridge, backgammon and other games. It is hardly surprising that a man who was so impatient to get into the army and be an actuary should also invent a rule to speed up backgammon play. Although the Jacoby rule is widely used in money matches it is rarely applied in competition matches.

Felicity Stone - Technical Writer