Introduction

Bill is a rather below average player, rated Intermediate by Snowie. I was singing Snowie's praises but Bill countered with derogatory remarks about computers and their lack of imagination. The result was a "Put your money where your mouth is" confrontation. Bill agreed to play a five point match against Snowie. If Bill won I would pay him £10 and if Snowie won, Bill would pay me £5. In this particular game Bill only reached a rating of Novice compared to his overall rating of Intermediate.

Terms

Equity
The expected value of a backgammon position. Specifically, the sum of the values of the possible outcomes from a given position with each value multiplied by its probability of occurrence.

If the difference in equity between the 'best' move and the one made is 0.02 or more the move is an error. If the difference is 0.08 or more it is a blunder. The difference is shown in brackets. Numbers not in brackets are the actual equities. The actual move played is denoted with a capital letter A.

Snowie leads 2-1

The old fashioned 13/8 13/10 with the 53 is rated 0.064

Black to play 41

13/8 is not aggressive enough.

Black to play 54

This is a blunder. 13/8 13/9 makes the useful 9-point as a block and provides a builder on the 8-point that helps to make the 7-, 5- or 3-points. Hitting loose on the 1-point should never be done without careful consideration.

Black to play 11

9/7(2) is by far the best. Bill's plan, leaving the blot on the 8-point takes an unnecessary chance.

Black to play 62

Black should have doubled prior to his roll of 62, raising his equity from 0.320 to 0.532. It is a common error not to take the score into consideration. There is a big difference between doubling when 1-2 down and when 2-1 up in a 5-point match

Black to play 33

This was a clear double for Black and he missed the opportunity. White must pass, although he wins 31.6%, the probability of being gammoned is too great.

Black on roll. Cube Action?

A clear double and an equally clear pass.

Note the very high luck rate of 5.445 for Black. The fact that the weaker player can get lucky and win helps to make backgammon the fascinating game it is. In this case Bill, an Intermediate played at Novice level and yet beat Snowie playing at Extra-Terrestial level. Happily my money was safe...Snowie went on to win the match 5-3 and Bill coughed up his fiver!