In this article we are taking a look at a relatively simple bear-off position. Should black double? Should white take if doubled?
In bear-offs we are unable to use our Race/Threat/Position/Opponent criteria to evaluate the position. We should still factor in the opponent but most of what we do know about bear-offs we know through study and the accumulation of a number of reference positions.
For example we know that a 3-roll vs 3-roll ending as shown below means a double for black and a drop for white.
White wins only 21.2% of the time which nowhere near the 25% he needs to take. Also white never gets to redouble.
In the 4-roll vs 4-roll position shown below the cube action is now double/take:
White now wins about 27% of the time and occasionally gets to use the cube to good effect. However beware. If we change this position by one pip to:
The cube action reverts to double/drop. This is because double ones no longer result in bearing off four men and white may also throw four successive 1’s and on the last turn will not be able to bear-off his last checker. Small differences can mean a lot in backgammon.
When we make judgements in a bear-off we mentally refer to positions such as the ones above and compare. In our first position both sides have five checkers each so initially we might think it is a 3-roll vs 3-roll position and use that benchmark. But black in particular may well take 4 rolls (for example look what happens if black roll 42 followed by 42). It looks as if it is roughly a 3½ roll vs 3-roll position. This should give you the answer that white will have a comfortable take.
Does black have a double? Barely – the position is volatile enough that by next turn black may well have lost his market so he must double now. Snowie confirms this: