Backgammon Doubling Cube Study

From: PhilSimborg   

Dear Phil:

Wow! Another wonderful, insightful article.

Signed, Annonymous.

From: RichMunitz   

I have the opposite problem. I am almost exclusively a match player and my judgment of correct money play is "what would I do in a long match tied 0-0. I looked at the position and my gut reaction to the money question was Pass. A very short rollout said Pass by a hair, but way too close and too short to call. That said, you are dead on about the effect of gammons at score and how strongly it can influence decisions - not only cube decisions, but also checker play decisions.

The interesting thing to keep in mind about match play vs. money play when 4-away, 4-away or greater is that gammons are pretty much ALWAYS worth more than in money play, regardless of who is ahead and who is behind on either a centered or 2-cube. The gammon value at score varies greatly - from an upper limit of about twice the money value down to a few cases where it is the same as money (0.50) or perhaps 0.49. But the lesson is that unless you actually know the gammon price at a given match score, you should always assume they are worth more than for money.

Where does the gammon price .69 come from? Such a specific number must result from some calculation, but I have no idea what calculation. Also, taking the gammon frequency times the gammon price resulted in "6 extra points" in match play at 5-away, 5-away versus money play. What does that mean? If it was only 3 extra points, would it be a take in the match? Does that calculation have any value?

The obvious point of the article is that the effect of gammons is magnified in match play, and adjustments need to be made in evaluating positions which recognize that fact.

Every time I think I'm getting there, somebody makes me feel small again.

From: PhilSimborg   

You raise an excellent point whaat--when you evaluate your position you consider not only the the number of times you lose and get gammoned, but also the times you win games and win gammons (and backgammons).

In money games this is always much easier as the price of gammons is always .5 for both sides while in match play the price can be different for each side depending on the difference in their score.

I did not go into this in detail in this article as I did not want to make things too complicated--I wanted to make the point that there is a major difference between match and money, and it takes study to understand the differences.

I write pretty much the way I teach--I try to keep it simple and avoid really complicated math. I've been teaching beginner and intermediate players for some 20 years and I find that it's counter-productive to get too deep into the math. As my students progress and become Open players, then I kick them up a level (by passing them off to the very people who have been teaching me, like Perry Gartner, Ray Fogerlund, Mary Hickey, and others).