This week we take a look at the complex world of doubling. There are four things we need to consider when doubling:
The Race. Backgammon is primarily a race so normally winning the race means winning the game. There are some obvious exceptions eg, when you have checkers trapped behind an opponent’s prime but the race is a good guide.
The Position. Who has the best static features in the position? By this i mean things like home board points, anchors in your opponent’s board, primes or potential primes and the number of blots.
The Threat. Do you have threats and in particular do you have threats, which if carried out, would mean that your opponent would no longer take next turn? A threat would include things like hitting a blot, making a key point in your home board, or extending/completing a prime.
The Opponent. Unless you are playing a computer you will need to take your opponent into consideration. How will he/she react to being doubled? Is he/she someone who drops takes or conversely takes drops?
The generally accepted view is that you should consider doubling if you are ahead in two of the first three elements and use the fourth element to help you make your final decision.
In the chouette from which this position was taken, white had erroneously played a 62 by moving 15/9, 3/1*. This minimised black’s shots to 15 instead of 18 after the correct 15/9, 15/13 but it exposed three blots instead of one.
Let us evaluate the position.
Black is behind by 20 pips before the roll. Advantage lies with white.
Black has the stronger home board of the two and an anchor in white’s home board. White’s position is something of a mess with there being too many checkers on his 1-pt and 2-pt. Advantage to black
White has three vulnerable blots and if black hits one of them he may well pick up at least one of the other two. Black will win a lot of gammons because of his strong home board. Note also that white won’t be able to redouble black even if he should stay on the bar. The position is highly volatile as after nearly any hit by black white would be dropping next turn. Advantage black
Not a big factor in this position as white is a good player who makes well-balanced cube decisions.
The key question is whether black will win enough gammons after hitting to make up for the fact that he is not favourite to hit from the bar. This can really only be judged from experience as it is nearly impossible to do so over the board.
In the chouette the team correctly judged that they would win enough gammons and doubled. White correctly took, black rolled 12, hit the blot on white’s 1-pt, picked up the other two and won a gammon.
The Snowie rollout above shows that both black and white made the right cube decisions.
Note that had white played his 62 correctly, 15/9, 15/13, and you then applied the criteria above you would find that black would not have had a double.
The key lessons are :
- Do not expose unnecessary blots when your opponent has a strong home board.
- Learn to use the criteria above to make your doubling decisions.