Black was hoping for a double to clear his mid-point but luck has deserted him and now he has to play this 43. After discarding the horrible 13/9, 4/1 there are only two plays: (a) 13/6 and (b) 13/9, 13/10. Surely not too difficult a problem and one that most people would get right in live play? Unfortunately this statement is not true as I have used this position many times with pupils and a fair percentage get it wrong. There is a very large difference in equity between the two plays. One of the plays is a blunder – Do you know which one?
Here are the typical arguments for both plays
Play (a) is clearly correct. We get one checker to safety and we are then playing with only one blot. If it is hit (twenty four numbers out of thirty-six do hit next turn) then we may be able to scramble it home. White may well double before he rolls but with only one blot I think we can take. If we make play (b), get hit and then fan, having the other blot means we can’t take a double next turn. Play (b) is less shots (twenty-one) but far more dangerous.
Play (b) is clearly correct. We leave only twenty-one shots versus twenty-four shots with play (a). Even if one checker does get hit most of our entering numbers will safety the other blot. The two blots are really an illusion – it’s minimizing the number of shots that counts. Also, with only twenty-one shots I don’t think white can double.
So which argument do you personally prefer?
As I stated above the decision is not close (see the Snowie evaluation) and in fact play (b) is the clear winner. The vital factor is minimizing the number of shots. Look at it this way – play (a) increases white’s hitting chances by 14% – that’s a huge percentage in backgammon terms. Too many players are deceived by the fact that play (b) exposes two blots and they choose play (a).
As with all positions in backgammon it is crucial to understand the dynamics of a position and then choose a game plan that meets the requirements of the position. Here that plan is to get home while leaving as few shots as possible. Note also that with both plays if white misses black will double him out.
I have had some pupils double from the white side after play (b) because of two blots. This is a huge error as white only a marginal favourite and when he misses, as we have already seen, he cannot take a redouble. Even after play (a) white is not strong enough to double
This is an very good reference position because this type of problem occurs time and time again.