The position is from a GridGammon match I watched. Here's a rollout at the score:
The score (after 9 games) is: White 8, Blue 9 (match to 11 points)
Move number 11: Blue to play 22
| White | 136 | ||
|---|---|---|---|
                        | |||
| Blue | 135 | ||
| Position ID: M23gYAjB84ZhAA Match ID: cAlpAYAASAAE | |||
• Blue moves 17/15(2) 6/4(2)
Alert: very bad move ( -0.111)
| # | Ply | Move | Equity | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | R | 17/15(2) 13/11(2) | +0.3220 | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 648 games, Mersenne Twister dice gen. with seed 932765888 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 2 | R | 13/9(2) | +0.2745 ( -0.0474) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 648 games, Mersenne Twister dice gen. with seed 932765888 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 3 | R | 13/11(2) 6/4(2) | +0.2708 ( -0.0512) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 648 games, Mersenne Twister dice gen. with seed 932765888 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| • | 4 | R | 17/15(2) 6/4(2) | +0.2115 ( -0.1105) | ||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 648 games, Mersenne Twister dice gen. with seed 932765888 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 5 | R | 17/13(2) | +0.2011 ( -0.1209) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 648 games, Mersenne Twister dice gen. with seed 932765888 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
I wonder if anyone besides Blue here and I ever have a problem with doublets?
They're often misplayed. The misplays are often large errors. The plays we choose look reasonable when we make them, but often look clearly wrong after some thought, after we see the best move.
Perhaps this is because there may be many ways to play a doublet, the various details of a position compete for our attention, different plays cater best to different factors, and the difference in how plays cater to those factors grows large with doublets, because rolling a doublet is very much like being able to take two turns in a row. It's hard to keep all the factors balanced as we consider various plays. The wrong play we end up making may look good at the time because it does cater well, even best, to some details of the position. But not to all the details properly balanced.
Much could be said about the particular details of this position -- the race, the home boards, the stacked 6 and 8 points, the stripped 9, 13 and 17 points, the competing needs to make good points, improve distribution, and bring stragglers home. But even when I can't balance all the considerations properly, I find that when the wrong doublet play looks right when I make it, and afterwards so wrong that I wonder how I could possibly have made that play, there is one thing I can often observe about the right doublet play: it was the prettiest play because it was the one that best kept all the checkers working together.
To be sure there are many exceptions. Sometimes we have an anchor that needs keeping while the rest of our position moves forward. Sometimes we should overextend our front position by using our "two turns in a row" to attack with extra doublet power tempo.