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The slotting option

Posted By: Chuck Bower
Date: Wednesday, 30 December 2009, at 2:30 a.m.

In Response To: Containment checker play, take 2 (Chuck Bower)

All at DMP.

Case 1: keep Blue's position the same; bear off White checkers (and simultaneously deteriorate White's board strength) until slotting is equally as good as not slotting.

The score (after 0 games) is: JellyFish 0, Player2 0 (match to 1 point, post-Crawford play)

Move number 9: Player2 to play 45


2X2X3X3X ' '1O '1O1O ' '

2O2O2O2O2O ' ' ' '1O '1O

Pip counts: JellyFish 52, Player2 101
Position ID: 2x0AALRtg0QJAA Match ID: cAk2AAAAAAAA

• Player2 moves 16/11 10/6

# Ply Move Equity
1 R 16/11 10/6 +0.2380
0.61900.00000.0000-0.38100.24800.0307 +0.2380 +0.2380
0.00050.00000.0000-0.00050.00110.0010 0.0010 0.0010
Full cubeful rollout with var.redn.
12969 games, Mersenne Twister dice gen. with seed 868869504 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 16/11 15/11 +0.2373 ( -0.0008)
0.61860.00000.0000-0.38140.22180.0183 +0.2373 +0.2373
0.00050.00000.0000-0.00050.00150.0008 0.0009 0.0009
Full cubeful rollout with var.redn.
12969 games, Mersenne Twister dice gen. with seed 868869504 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 4 16/12 15/10 +0.1919 ( -0.0461)
0.5959 0.0000 0.0000 - 0.4041 0.1197 0.0042
4 2 15/6 +0.2334 ( -0.0046)
0.6167 0.0000 0.0000 - 0.3833 0.2325 0.0161
5 2 18/13 10/6 +0.2053 ( -0.0327)
0.6026 0.0000 0.0000 - 0.3974 0.2206 0.0109
6 2 12/7 10/6 +0.1348 ( -0.1032)
0.5674 0.0000 0.0000 - 0.4326 0.2528 0.0127
7 2 18/13 16/12 +0.1275 ( -0.1105)
0.5638 0.0000 0.0000 - 0.4362 0.1007 0.0025
8 2 18/14 16/11 +0.1244 ( -0.1136)
0.5622 0.0000 0.0000 - 0.4378 0.1322 0.0049
9 2 18/14 15/10 +0.1109 ( -0.1271)
0.5554 0.0000 0.0000 - 0.4446 0.1007 0.0018
10 2 18/13 15/11 +0.1084 ( -0.1296)
0.5542 0.0000 0.0000 - 0.4458 0.1323 0.0051

Slotting improves in value for two reasons: 1) If hit Blue has chances of entering and catching White on his way around; 2) White's improved racing chances mean Blue has more incentive to make the 6-point and prevent White from entering until Blue has checkers borne off (i.e. after catching up in the race.)

Case 2: Put Blue's rearmost checker in his homeboard, reducing the number of outfield builders/shooters to four from the original five. Now deteriorate White's position until slotting is roughly equal in equity to not slotting.

The score (after 0 games) is: JellyFish 0, Player2 0 (match to 1 point, post-Crawford play)

Move number 11: Player2 to play 45


2X2X2X3X3X ' ' '1O1O ' '

2O2O2O2O3O ' ' ' '1O '1O

Pip counts: JellyFish 64, Player2 88
Position ID: 2+4AANC2HSQKAA Match ID: cAk2AAAAAAAA

• Player2 moves 16/11 10/6

# Ply Move Equity
1 R 16/11 10/6 +0.2748
0.63740.00000.0000-0.36260.23540.0158 +0.2748 +0.2748
0.00060.00000.0000-0.00060.00370.0015 0.0013 0.0013
Full cubeful rollout with var.redn.
3564 games, Mersenne Twister dice gen. with seed 868869504 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 15/6 +0.2732 ( -0.0016)
0.63660.00000.0000-0.36340.23480.0151 +0.2732 +0.2732
0.00070.00000.0000-0.00070.00360.0015 0.0013 0.0013
Full cubeful rollout with var.redn.
3564 games, Mersenne Twister dice gen. with seed 868869504 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 16/11 15/11 +0.2609 ( -0.0139)
0.63050.00000.0000-0.36950.15220.0073 +0.2609 +0.2609
0.00070.00000.0000-0.00070.00350.0011 0.0014 0.0014
Full cubeful rollout with var.redn.
3563 games, Mersenne Twister dice gen. with seed 868869504 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 16/12 15/10 +0.2492 ( -0.0256)
0.62460.00000.0000-0.37540.09950.0039 +0.2492 +0.2492
0.00060.00000.0000-0.00060.00310.0007 0.0013 0.0013
Full cubeful rollout with var.redn.
3564 games, Mersenne Twister dice gen. with seed 868869504 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 2 15/10 5/1 +0.1964 ( -0.0783)
0.5982 0.0000 0.0000 - 0.4018 0.0420 0.0009
6 2 16/11 5/1 +0.1647 ( -0.1100)
0.5824 0.0000 0.0000 - 0.4176 0.0987 0.0044
7 2 16/7 +0.1386 ( -0.1362)
0.5693 0.0000 0.0000 - 0.4307 0.0929 0.0043
8 2 16/12 10/5 +0.1365 ( -0.1383)
0.5682 0.0000 0.0000 - 0.4318 0.0248 0.0004
9 2 12/7 10/6 +0.1350 ( -0.1398)
0.5675 0.0000 0.0000 - 0.4325 0.2272 0.0112
10 2 15/10 12/8 +0.1327 ( -0.1421)
0.5663 0.0000 0.0000 - 0.4337 0.0411 0.0007

With just one less outfield checker to work with, Blue must slot earlier (i.e. only 2 White checkers borne off instead of 4 and only one open point in White's board compared to the previous position).

My recollection of these class of positions is that you usually have only a few checkers in the outfield (two or three) to work with. As follows from above, slotting the open homeboard point is then more of a realistic option.

Similar tweaking can be done for the more common situation of gammons counting to find the tipping points for those.

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