It’s Not WHAT You Think – It’s HOW

by Joe Sylvester

(This article first appeared in the Flint Backgammon News in January, 1988.)

Very often I am confronted by players who ask about a doubling position and what the right answer should be. Instead, they should be asking how to work out the answer. They should be weighing the main components of the situation in order to make a wise decision. Just what are those components…?

Every position can be evaluated in terms of:

• Pips (Race)
• Position (Checker Distribution)
• Vigorish (Threats)

Basically, if a player has an advantage in two of these three components, he should double.

If the player doubled has an advantage in one of these components, he usually has a take.

It’s when the player doubled has a disadvantage in two components and is equal in the third that borderline decisions occur.

Here are some examples (eXtreme Gammon rollouts  follow the article.):

POSITION 1

Sly1

In this position, Red is down in pips, his position is undeveloped and his vigorish is very minimal. All he has is an anchor. Black has a strong double and Red should drop. This is a sucker double.

POSITION 2

Sly 2

In this position Black has a slightly better position than Red, and Black is ahead in the race. Red has something to fight back with, however. Red has an advanced anchor, good checker distribution, comparable board strength, and some small priming possibilities. Here, Black should double, and Red should take.

Keep in mind that in evaluating these component factors, the component must be relevant. For example, a player with 14 men on his ace-point and a checker caught behind a prime is clearly ahead in pips. Just as clearly, he has a drop.

Rollouts

POSITION 1

Sly1

Sly1rollout

POSITION 2

Sly 2

Sly2 rollout

Sly 2015 – In retrospect, I see that there are no market losers and the 3-point game is very resilient.  BUT – keep in mind, that 17.5% wrong passes would justify the double!  So know your opponent!  And, remember that it is an intimidating position that will in fact draw some incorrect passes.

Concepts in Action

by Joe Sylvester

(This article originally appeared in the Flint Backgammon News January, 1989)

Editor’s Note: When reading the article below, keep in mind that while a number of computer programs can give you the correct answer to the question posed, those programs will not be available to you over the board in a live tournament situation. And so, it is important that you be able to form accurate estimates of wins, losses and gammons over the board. For the overall match equity, you can refer to any number of tables, one of which can be found here: http://www.pion.ch/backgammon/mem-met.php

When gammons are a possibility in a game, determining take points becomes much more complex. The ability to evaluate positions becomes of the utmost importance.

Let’s assume the score is 4-3 in a match to 9 points. The following position occurs, and we, the leader, are doubled…

1(eXtreme Gammon™ rollout is shown at the end of the article.)

At this point, we must evaluate the following probabilities:
• % of Games Taken & Won
• % of Games Taken & Lost
• % of Games Taken & Gammon Won
• % of Games Taken and Gammon Lost

If we take, our match equity is the sum of these percentages times the resulting score’s match equity. This figure compared to our match equity if we pass determines our action.
Let’s assume we evaluate example 1 as follows:

• 30% Wins = Score of 6-3 or 73% (50+9+8+6)
• 40% Losses = Score of 4-5 of 41% (50-9)
• 5% Wins Gammon = Score of 8-3 Crawford of 90%
• 25% Loses Gammon = Score of 4-7 or 27% (50-9-8-6)

If we take, our equity is:

.30 X .73 = a21.9
.40 X .41 = a16.4
.05 X .90 =   a4.5
.25 X .27 =   a6.8
aaaaaaaaaa49.6

If we pass, the score is 4-4 or 50%. The decision is borderline. At this point, we may wish to reevaluate the position and/or our opponent’s relative strengths and weaknesses. For example, how does he handle this type of blitz position? How will my opponent’s play be affected by a win? A loss? A gammon?

IMPORTANT! Clearly the final evaluation is arbitrary. The number of wins, losses and gammons is absolutely the most important, crucial evaluation in all of tournament backgammon. One person using a different evaluation than the next may find this position an absolute drop, while the next person might question whether he should have been doubled or not.

I strongly urge you to evaluate this position on your own, and use whichever equity chart or sequence you wish. Try out your evaluation at different scores.

Remember, no answer is absolute. In middle game situations we can only estimate. However, your estimations can help you form a much more accurate cube decision.

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