Play Backgammon for free. The software is downloadable and has a chat feature included when playing against other players. Tournaments can also be played for Fun. To start playing simply download and open a new table or join a table.
Equity in Backgammon
All of us know the importance of the term equity in finance, whether in business or personnel wealth. In general the meaning of equity is value of ownership. In backgammon we use the term equity to indicate expectation. If one needs to calculate the chances of winning or losing in the game, the best method is to analyse the equity of the game like statisticians.
In backgammon we talk of two types of equity. In the absence of the doubling cube we call it cubeless equity while in its presence the equity it is known as cubeful equity.
But how is equity calculated in backgammon? Let's take an example of a situation, where the player one is in a position, where he feels, he has got 60% chance of winning, 10% likely to win a gammon and he faces a 20% chance of losing the game. So the equity becomes .6 + .1*2 - .2, which equals .6. So the equity of the game is in the favour of player one at 60%. In a money game, if somebody takes over the game from a particular position he pays you the equivalent of that equity factor based on the unit price of a point, the players are playing.
But this equity factor may change with every shot, rather than with every roll. Therefore you need to calculate equity with every shot. If one shot earns equity of 60% and the immediate subsequent shot earns equity of 50%, the prior move has to be said to be 10% better than the subsequent one.
The example cited above is the equity of a particular game. There is another equity available in backgammon, which is called the match equity. Or, the chances of winning the match. Take this example, where the opponent has already won the first 2 games in a Crawford game. At this situation, you need to win two games in a row to equalise and keep the fifth game alive. So, at this stage your odds are .5 * .5, which yields 25%. But your opponent has gained match equity of 75%.
What then is the difference between cubeful and cubeless here? To get the cubeful equity one has to multiply the current value of the doubling cube with the cubeless numbers. The one major factor in case of a cubeful equity is the ownership of the doubling cube. How is that taken into account? An additional 5 to 10% gets added to the equity value of the owner of the doubling cube, and a parallel deduction of an equity percentage takes place from the player who does not own the doubling cube at that point of time.
Equity is not necessary when playing a friendly game, but in a money game that's an entirely different proposition.
