## Advanced Strategy for Backgammon Doubling

Though backgammon has been around for 2,000 years, the introduction of the doubling cube in the mid-1920s in New York revolutionized the game and took it to the next level. The next level is to play backgammon online, against many opponents, and to win.

The doubling cube elevated backgammon from an interesting game of racing to beat your opponent in getting all 15 of your checkers off the board and blocking his moves to an intriguing game of strategy and skill.

## Here are some things every player needs to know about doubling:

The doubling cube is slightly larger than regular dice and has six sides marked with these numbers - 2, 4, 8, 16, 32 and 64 - that basically serve to mark the value of the game.

At the beginning of each game, the cube is placed in the center of the bar with the "64" side facing up. At any point during the game, the player set to roll can turn the cube to "2" and offer a double by saying "I double" instead of rolling his dice.

His opponent has two choices: give up the game, losing a point and set up the pieces for the next game. Or he can accept the cube and the value of the game is doubled, meaning a single win is worth 2 points, a gammon worth 4 points and a backgammon worth 6 points. Having accepted the cube, only he has the right to redouble to the 4-level at some future point of the game.

Among experienced players, most games end at the 1, 2 or 4-level. In games lasting a few hours, you might see a few 8-cubes. It is very rare to see a double cube reach the 16-level. And games with 16 and 32-cubes being used indicate players who don't know what they are doing.

## So how do you know when to take a double?

Take a double only if you have at least a 25 percent chance of winning the game and are unlikely to lose a gammon or backgammon. If you can be gammoned, you need better than a 25 percent chance of winning to take a double. How much depends on how likely you are to lose a gammon, so anticipate potential problems that lie ahead for you in the game and let that guide your decision making.

Deciding to drop a game when someone offers you a double is easy because you know exactly how much you'll lose. Evaluating whether to take a double is more difficult. The more experienced you are, the better you'll be able to analyze a game and make the right decision.

## How do you know when to offer a double?

Offering a double is more complicated than accepting one. On one hand, you don't want to double too late because your opponent will give up, leaving you able to win only one point vs. a possible two or four through a gammon or backgammon. On the other hand, doubling too early will give your opponent too many chances to turn the game around.

The rule of thumb is that you only offer an initial double if your chances of winning are 68 to 69 percent or more; you offer a redouble if your chances of winning are greater than 71 to 72 percent. During the game, there's no way to realistically calculate your chance of winning, but with experience you'll learn to make a reasonable estimate. The better you get at estimating, the stronger a player you'll become.

• Am I in a better position than my opponent? To answer this question, consider whether you are ahead in the race, have more blocking points, more back checkers advanced and whether your opponent is on the bar.
• Could the position change decisively in my favor on the next roll? - This involves evaluating whether you are on the verge of crushing your opponent.

If the answer to both questions is yes, doubling or a redouble are a good option to consider.

Remember this: just because you can double with sure knowledge your opponent will pass doesn't mean you should. Though having your opponent pass on the double assures you of two points, if you kept the cube and continued playing you have the possibility to win a gammon and score four points. If lucky, you could score backgammon and six points.

## The Jacoby Rule

In most backgammon clubs around the country, head to head games are played with the Jacoby rule. Designed to speed up play and prevent long boring games, the Jacoby rule says no gammon can be scored unless a double has been played and accepted.

The downside is that you can only play n for a gammon if you already own the double cube and not if it is still centered. The Jacob rule is not used in tournament play.

## Playing with Beavers

The beaver rule is an optional rule in money play that allows you, when doubled, to turn the cube one extra level and still retain ownership. You must beaver immediately upon being doubled.

Here's how it works: white, owning the cube on 2, decide to double to 4. Instead of taking the cube, white catches this bad mistake and turns it one more notch to 8, keeping it on his side and announcing, "I beaver."

After you beaver, you can redouble to 16 on your next turn if you want. Beavers add an extra measure of skill to the game. The beaver adds an extra twist to doubling rules and is a great way to punish players who use doubles unwisely.

If you are playing a private game, you should ask if beavers are permitted. Beavers are never allowed in tournament play.