Wiggins’s Boards, Blots, and Double Shots

Norm Wiggins’s excellent book Boards, Blots, and Double Shots is based on Jellyfish rollouts. Jellyfish was the strongest backgammon program available at the time, but since then, stronger programs have emerged (though still based on the same neural net paradigm). In 2007, Torsten Schoop ran a head-to-head competition among several bots. The results of this “Big Bot Shoot-out” were that Jellyfish was decidedly weaker than BGBlitz, Snowie, and GNU Backgammon, with GNU doing the best. In 2010, Michael Depreli organized a bot comparison project to compare BGBlitz, Snowie, GNU, and eXtreme Gammon (version 1). The strongest bot according to this project was eXtreme Gammon.

It is therefore interesting to see whether eXtreme Gammon disagrees with Jellyfish on any of the positions in the book. I manually entered all the positions, as well as some variants mentioned by Wiggins in his analysis, into eXtreme Gammon version 1.21. Where XG Roller+ indicated that there might be an issue of some sort, I asked my friend Miller Maley, who owns eXtreme Gammon version 2.00, to perform a full rollout. The most interesting results of this study are presented below. All rollouts below were done with eXtreme Gammon version 2.00.

The most dramatic disagreements between the two bots occur in positions 3, 14, and 89. Other notable disagreements include positions 60, 72, 80, 92, 100, 102, 118. I have also included a number of other rollouts for reasons explained in more detail below.

Except where otherwise specified, the rollouts below assume that the Jacoby rule is in effect. Wiggins is not entirely clear about whether the Jacoby rule is supposed to apply in all the positions in the book. His comments on Positions 80 and 93 suggest that Jacoby should be assumed to apply. However, in Problem 114, he talks about being too good to double with the cube in the center. The question is somewhat moot because I believe it is very unlikely that the Jacoby rule will affect which play comes out on top in any of the positions in the book (unless two or more plays are almost tied for top). For a general explanation of why the Jacoby rule rarely makes a difference when it comes to checker plays, see this article that I posted to rec.games.backgammon.

I should mention that for many of the positions in the book, the absolute equity figures of XG differ substantially from Jellyfish’s; however, if the overall qualitative verdict (i.e., which play is best, and by a large or a small margin) remains the same, then I have usually not bothered to include the rollout here.

NOTE: I have included rollout information only and have not included diagrams of the positions. This is intentional. I do not want to violate copyright, and I do not want this website to act as a partial substitute for Wiggins’s book. It is intended solely as a study tool for those who have already purchased the book.


Position 3

One of the most dramatic results of this study. Jellyfish prefers 6/5*/2, which XG thinks is a whopper.

1.Rollout113/10 6/5* eq: -0.070
Player:
Opponent:
42.58% (G:27.47% B:1.05%)
57.42% (G:30.12% B:3.79%)
Conf: ± 0.007 (-0.077...-0.063)
Duration: 16 minutes 00 second
2.Rollout16/5* 5/2eq: -0.194 (-0.124)
Player:
Opponent:
42.53% (G:21.89% B:0.44%)
57.47% (G:20.47% B:0.85%)
Conf: ± 0.007 (-0.201...-0.187)
Duration: 31 minutes 32 seconds
3.Rollout113/10 11/10eq: -0.347 (-0.277)
Player:
Opponent:
40.09% (G:14.64% B:0.23%)
59.91% (G:16.12% B:0.61%)
Conf: ± 0.007 (-0.354...-0.340)
Duration: 38 minutes 35 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

Below is a rollout with the Jacoby rule turned off. This is one of those rare positions where the Jacoby rule makes a detectable difference. With the Jacoby rule in force, 13/10 6/5* forces White to double from the bar in order to reap the full benefit of hitting back, whereas without Jacoby, White can leave the cube in the center and play on for a gammon when she hits back. Thus 13/10 6/5* is relatively less attractive without Jacoby, but it still rolls out way ahead of the alternatives.

1.Rollout113/10 6/5* eq: -0.132
Player:
Opponent:
42.60% (G:27.47% B:1.05%)
57.40% (G:30.01% B:3.66%)
Conf: ± 0.004 (-0.136...-0.128)
Duration: 20 minutes 53 seconds
2.Rollout16/5* 5/2eq: -0.215 (-0.083)
Player:
Opponent:
42.63% (G:22.00% B:0.41%)
57.37% (G:21.45% B:0.79%)
Conf: ± 0.007 (-0.222...-0.208)
Duration: 40 minutes 09 seconds
3.Rollout113/10 11/10eq: -0.346 (-0.214)
Player:
Opponent:
40.13% (G:14.59% B:0.21%)
59.87% (G:16.44% B:0.58%)
Conf: ± 0.006 (-0.352...-0.340)
Duration: 38 minutes 54 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


For reference, here is a rollout of White’s cube decision from the bar after 13/10 6/5* if the Jacoby rule is in force:

Analyzed in Rollout
No Double
  Player Winning Chances: 57.17% (G: 28.34% B: 3.05%)
  Opponent Winning Chances: 42.83% (G: 27.04% B: 1.08%)
Double/Take
  Player Winning Chances: 57.43% (G: 30.26% B: 3.70%)
  Opponent Winning Chances: 42.57% (G: 27.53% B: 1.10%)
 
Cubeless Equities
No Double:+0.143
Double:+0.404
 
Cubeful Equities
No Double:-0.010 (-0.079)
Double/Take:+0.068
Double/Drop:+1.000 (+0.932)
 
Best Cube action: Double / Take
 
Rollout details
2592 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.004 (-0.014...-0.007)
Confidence Double: ± 0.008 (+0.060...+0.077)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 11 minutes 31 seconds


And here is a rollout of White’s cube decision from the bar after 13/10 6/5* if the Jacoby rule is not in force:

Analyzed in Rollout
No Double
  Player Winning Chances: 57.44% (G: 30.13% B: 3.63%)
  Opponent Winning Chances: 42.56% (G: 27.52% B: 1.10%)
Double/Take
  Player Winning Chances: 57.43% (G: 30.27% B: 3.70%)
  Opponent Winning Chances: 42.57% (G: 27.53% B: 1.10%)
 
Cubeless Equities
No Double:+0.200
Double:+0.404
 
Cubeful Equities
No Double:+0.137
Double/Take:+0.068 (-0.069)
Double/Drop:+1.000 (+0.863)
 
Best Cube action: No Double / Take
 
Rollout details
2592 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.005 (+0.132...+0.142)
Confidence Double: ± 0.008 (+0.060...+0.077)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 16 minutes 24 seconds


Position 4

My play here was 6/5 6/4, which Wiggins does not even mention as a candidate. It comes in second place in the XG rollout.

1.Rollout124/22 6/5eq: -0.312
Player:
Opponent:
42.23% (G:6.92% B:0.25%)
57.77% (G:11.90% B:0.30%)
Conf: ± 0.006 (-0.318...-0.306)
Duration: 1 hour 53 minutes
2.Rollout16/5 6/4eq: -0.328 (-0.017)
Player:
Opponent:
42.01% (G:8.60% B:0.31%)
57.99% (G:13.78% B:0.43%)
Conf: ± 0.007 (-0.335...-0.321)
Duration: 1 hour 49 minutes
3.Rollout124/23 6/4eq: -0.351 (-0.039)
Player:
Opponent:
41.22% (G:8.04% B:0.29%)
58.78% (G:13.61% B:0.40%)
Conf: ± 0.006 (-0.357...-0.345)
Duration: 1 hour 28 minutes
4.Rollout116/15 6/4eq: -0.358 (-0.047)
Player:
Opponent:
41.09% (G:8.34% B:0.31%)
58.91% (G:13.65% B:0.40%)
Conf: ± 0.006 (-0.364...-0.352)
Duration: 1 hour 31 minutes
5.Rollout116/13eq: -0.362 (-0.050)
Player:
Opponent:
40.93% (G:6.35% B:0.22%)
59.07% (G:11.60% B:0.23%)
Conf: ± 0.006 (-0.368...-0.356)
Duration: 1 hour 28 minutes
6.Rollout124/21eq: -0.376 (-0.064)
Player:
Opponent:
40.75% (G:5.43% B:0.21%)
59.25% (G:12.42% B:0.31%)
Conf: ± 0.006 (-0.382...-0.370)
Duration: 2 hours 32 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 14

A dramatic disagreement: the top play by a clear margin in the XG rollout is not even mentioned by Wiggins!

1.Rollout113/7 9/8eq: +0.130
Player:
Opponent:
53.66% (G:18.10% B:1.17%)
46.34% (G:18.37% B:1.98%)
Conf: ± 0.009 (+0.121...+0.139)
Duration: 41 minutes 04 seconds
2.Rollout113/6eq: +0.091 (-0.039)
Player:
Opponent:
51.77% (G:19.36% B:1.36%)
48.23% (G:16.47% B:1.21%)
Conf: ± 0.008 (+0.083...+0.099)
Duration: 37 minutes 19 seconds
3.Rollout124/18 10/9eq: +0.071 (-0.059)
Player:
Opponent:
53.95% (G:20.30% B:2.11%)
46.05% (G:22.03% B:0.65%)
Conf: ± 0.008 (+0.063...+0.079)
Duration: 35 minutes 53 seconds
4.Rollout124/23 10/4eq: -0.007 (-0.136)
Player:
Opponent:
50.65% (G:19.68% B:1.65%)
49.35% (G:22.28% B:1.11%)
Conf: ± 0.009 (-0.016...+0.002)
Duration: 35 minutes 07 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

The play 13/7 9/8 is volatile enough that I thought the Jacoby rule might be relevant. However, the rollout below with the Jacoby rule turned off indicates that the Jacoby rule makes no difference.

1.Rollout113/7 9/8eq: +0.127
Player:
Opponent:
53.79% (G:18.04% B:1.17%)
46.21% (G:18.41% B:2.06%)
Conf: ± 0.009 (+0.118...+0.136)
Duration: 44 minutes 17 seconds
2.Rollout113/6eq: +0.091 (-0.037)
Player:
Opponent:
51.75% (G:19.47% B:1.36%)
48.25% (G:16.55% B:1.22%)
Conf: ± 0.007 (+0.084...+0.098)
Duration: 40 minutes 32 seconds
3.Rollout124/18 10/9eq: +0.072 (-0.056)
Player:
Opponent:
53.90% (G:20.42% B:2.14%)
46.10% (G:23.01% B:0.61%)
Conf: ± 0.008 (+0.064...+0.080)
Duration: 43 minutes 29 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

Position 16

Wiggins does not mention 21/18 8/7*; the XG rollout says that it is a top contender.

1.Rollout113/10 8/7* eq: +0.271
Player:
Opponent:
56.67% (G:17.65% B:0.89%)
43.33% (G:13.51% B:0.95%)
Conf: ± 0.008 (+0.263...+0.279)
Duration: 1 hour 11 minutes
2.Rollout121/18 8/7* eq: +0.266 (-0.005)
Player:
Opponent:
56.69% (G:16.75% B:0.82%)
43.31% (G:13.58% B:0.75%)
Conf: ± 0.008 (+0.258...+0.274)
Duration: 1 hour 10 minutes
3.Rollout18/7* 7/4eq: +0.238 (-0.033)
Player:
Opponent:
55.40% (G:17.82% B:0.82%)
44.60% (G:12.57% B:0.57%)
Conf: ± 0.009 (+0.229...+0.247)
Duration: 1 hour 11 minutes
4.Rollout18/5 8/7* eq: +0.218 (-0.053)
Player:
Opponent:
55.05% (G:16.62% B:0.73%)
44.95% (G:12.30% B:0.55%)
Conf: ± 0.008 (+0.210...+0.226)
Duration: 1 hour 07 minutes
5.Rollout121/18 5/4eq: +0.217 (-0.054)
Player:
Opponent:
55.92% (G:15.08% B:0.65%)
44.08% (G:13.22% B:0.46%)
Conf: ± 0.008 (+0.209...+0.225)
Duration: 1 hour 04 minutes
6.Rollout123/22 21/18eq: +0.200 (-0.071)
Player:
Opponent:
55.54% (G:15.53% B:0.70%)
44.46% (G:13.74% B:0.46%)
Conf: ± 0.007 (+0.193...+0.207)
Duration: 1 hour 04 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 23 (variant)

This is a rollout of the variant position, mentioned by Wiggins, in which White owns her 2pt instead of her midpoint. In this variant, Wiggins recommends bar/24 13/10, but XG prefers bar/24 6/3.

1.Rollout1Bar/24 6/3eq: -0.251
Player:
Opponent:
45.07% (G:5.51% B:0.20%)
54.93% (G:15.00% B:0.23%)
Conf: ± 0.006 (-0.257...-0.245)
Duration: 40 minutes 44 seconds
2.Rollout1Bar/24 13/10eq: -0.324 (-0.073)
Player:
Opponent:
43.32% (G:6.02% B:0.23%)
56.68% (G:18.42% B:0.26%)
Conf: ± 0.006 (-0.330...-0.318)
Duration: 36 minutes 48 seconds
3.Rollout1Bar/21eq: -0.365 (-0.114)
Player:
Opponent:
42.32% (G:6.51% B:0.26%)
57.68% (G:21.38% B:0.20%)
Conf: ± 0.005 (-0.370...-0.360)
Duration: 30 minutes 20 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 24 (subsequent cube action)

This is a rollout of White’s doubling decision after Black runs with 20/14. Wiggins implies that White does not have a double, but XG says that it would be a whopper for White not to double here.

Analyzed in Rollout
No Double
  Player Winning Chances: 70.15% (G: 10.83% B: 0.39%)
  Opponent Winning Chances: 29.85% (G: 3.31% B: 0.03%)
Double/Take
  Player Winning Chances: 70.67% (G: 11.80% B: 0.39%)
  Opponent Winning Chances: 29.33% (G: 3.81% B: 0.04%)
 
Cubeless Equities
No Redouble:+0.482
Redouble:+0.993
 
Cubeful Equities
No Redouble:+0.766 (-0.121)
Redouble/Take:+0.887
Redouble/Drop:+1.000 (+0.113)
 
Best Cube action: Redouble / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Redouble: ± 0.003 (+0.763...+0.769)
Confidence Redouble: ± 0.005 (+0.882...+0.892)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 30 minutes 12 seconds


Position 32

The only comment here is that 24/23 6/4* is a plausible candidate not mentioned by Wiggins.

1.Rollout111/10 6/4* eq: +0.350
Player:
Opponent:
62.66% (G:28.96% B:3.61%)
37.34% (G:7.37% B:0.34%)
Conf.: ± 0.006 (+0.344...+0.356) - [100.0%]
Duration: 4 hours 04 minutes
2.Rollout124/23 6/4* eq: +0.328 (-0.022)
Player:
Opponent:
62.49% (G:27.80% B:3.36%)
37.51% (G:7.57% B:0.35%)
Conf.: ± 0.006 (+0.322...+0.334) - [0.0%]
Duration: 2 hours 39 minutes
3.Rollout16/4* 4/3eq: +0.306 (-0.043)
Player:
Opponent:
60.85% (G:29.15% B:3.93%)
39.15% (G:7.26% B:0.33%)
Conf.: ± 0.006 (+0.300...+0.313) - [0.0%]
Duration: 2 hours 37 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 33

Contrary to what Wiggins says, XG thinks that 8/2* 4/2 is indeed Black’s second-best play.

1.Rollout124/16eq: -0.334
Player:
Opponent:
37.17% (G:9.45% B:0.51%)
62.83% (G:31.20% B:0.87%)
Conf.: ± 0.004 (-0.338...-0.329) - [100.0%]
Duration: 26 minutes 58 seconds
2.Rollout18/2* 4/2eq: -0.390 (-0.056)
Player:
Opponent:
32.99% (G:6.97% B:0.20%)
67.01% (G:22.89% B:1.16%)
Conf.: ± 0.004 (-0.394...-0.386) - [0.0%]
Duration: 23 minutes 41 seconds
3.Rollout124/18 4/2* eq: -0.413 (-0.080)
Player:
Opponent:
35.61% (G:6.94% B:0.31%)
64.39% (G:32.17% B:1.42%)
Conf.: ± 0.004 (-0.417...-0.409) - [0.0%]
Duration: 27 minutes 20 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 35

No real disagreement here but a long rollout indicates that XG thinks the top two plays are even closer than Jellyfish thinks.

1.Rollout124/21 6/4* eq: +0.130
Player:
Opponent:
53.42% (G:16.01% B:0.85%)
46.58% (G:14.78% B:0.85%)
Conf: ± 0.004 (+0.126...+0.134)
Duration: 5 hours 31 minutes
2.Rollout113/10 6/4* eq: +0.118 (-0.012)
Player:
Opponent:
53.14% (G:17.15% B:0.91%)
46.86% (G:15.66% B:1.18%)
Conf: ± 0.005 (+0.113...+0.123)
Duration: 5 hours 22 minutes
3.Rollout26/4* 4/1* eq: +0.051 (-0.079)
Player:
Opponent:
50.73% (G:17.22% B:0.69%)
49.27% (G:14.83% B:0.82%)
Conf: ± 0.008 (+0.043...+0.059)
Duration: 1 hour 19 minutes
 
1 20736 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

2 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 40

Though XG does favor 5/2 3/2 over 10/6*, it is by a much smaller margin, and its estimated cubeless statistics differ quite a bit from Jellyfish’s.

1.Rollout15/2 3/2eq: -0.400
Player:
Opponent:
40.18% (G:5.53% B:0.06%)
59.82% (G:13.73% B:0.36%)
Conf.: ± 0.005 (-0.405...-0.395) - [100.0%]
Duration: 25 minutes 35 seconds
2.Rollout110/6* eq: -0.424 (-0.024)
Player:
Opponent:
41.49% (G:9.62% B:0.13%)
58.51% (G:30.19% B:0.78%)
Conf.: ± 0.007 (-0.431...-0.417) - [0.0%]
Duration: 15 minutes 48 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 42 (variant)

This is a rollout of the variant position mentioned by Wiggins, in which we shift White’s 9pt forwards to the 8pt to make a solid five-prime. Wiggins says that the decision whether to hit “would be truly close…too close for comfort.” However, the XG rollout below says that hitting would still be very clear.

1.Rollout111/5 4/3* eq: +0.618
Player:
Opponent:
64.70% (G:43.98% B:8.27%)
35.30% (G:3.76% B:0.18%)
Conf: ± 0.005 (+0.613...+0.623)
Duration: 33 minutes 19 seconds
2.Rollout113/7 4/3* eq: +0.582 (-0.036)
Player:
Opponent:
64.02% (G:43.48% B:8.13%)
35.98% (G:4.99% B:0.38%)
Conf: ± 0.005 (+0.577...+0.587)
Duration: 30 minutes 08 seconds
3.Rollout110/3* eq: +0.553 (-0.065)
Player:
Opponent:
62.96% (G:42.40% B:8.00%)
37.04% (G:4.34% B:0.20%)
Conf: ± 0.005 (+0.548...+0.558)
Duration: 31 minutes 33 seconds
4.Rollout113/12 11/5eq: +0.513 (-0.105)
Player:
Opponent:
62.28% (G:38.25% B:6.65%)
37.72% (G:1.34% B:0.05%)
Conf: ± 0.005 (+0.508...+0.518)
Duration: 32 minutes 55 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 45 (variant)

If we move two of White’s checkers from her 8pt to her 7pt, then Wiggins says that 14/4 should be the top play. XG concurs, but just barely.

1.Rollout114/4eq: +0.922
Player:
Opponent:
81.60% (G:37.53% B:0.67%)
18.40% (G:2.60% B:0.10%)
Conf.: ± 0.003 (+0.918...+0.925) - [96.6%]
Duration: 24 minutes 20 seconds
2.Rollout114/8 6/2* eq: +0.917 (-0.005)
Player:
Opponent:
76.93% (G:51.76% B:1.00%)
23.07% (G:5.97% B:0.29%)
Conf.: ± 0.004 (+0.913...+0.921) - [3.4%]
Duration: 24 minutes 02 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 46

The main point here is that the XG rollout says that bar/22 6/4 is second best, but Wiggins does not mention it as a candidate.

1.Rollout1Bar/23 24/21eq: +0.238
Player:
Opponent:
55.28% (G:17.06% B:0.73%)
44.72% (G:10.47% B:0.48%)
Conf: ± 0.008 (+0.230...+0.246)
Duration: 1 hour 24 minutes
2.Rollout1Bar/22 6/4eq: +0.220 (-0.018)
Player:
Opponent:
55.10% (G:16.14% B:0.68%)
44.90% (G:10.40% B:0.46%)
Conf: ± 0.008 (+0.212...+0.228)
Duration: 1 hour 19 minutes
3.Rollout1Bar/20eq: +0.210 (-0.027)
Player:
Opponent:
54.76% (G:15.94% B:0.67%)
45.24% (G:10.84% B:0.50%)
Conf: ± 0.009 (+0.201...+0.219)
Duration: 1 hour 21 minutes
4.Rollout1Bar/22 8/6eq: +0.192 (-0.046)
Player:
Opponent:
54.38% (G:15.31% B:0.63%)
45.62% (G:10.22% B:0.43%)
Conf: ± 0.008 (+0.184...+0.200)
Duration: 1 hour 16 minutes
5.Rollout1Bar/23 7/4eq: +0.189 (-0.049)
Player:
Opponent:
54.19% (G:16.77% B:0.82%)
45.81% (G:12.00% B:0.65%)
Conf: ± 0.008 (+0.181...+0.197)
Duration: 1 hour 30 minutes
6.Rollout1Bar/22 7/5eq: +0.173 (-0.065)
Player:
Opponent:
53.87% (G:15.08% B:0.63%)
46.13% (G:10.45% B:0.45%)
Conf: ± 0.008 (+0.165...+0.181)
Duration: 1 hour 30 minutes
7.Rollout1Bar/22 24/22eq: +0.171 (-0.067)
Player:
Opponent:
53.95% (G:14.45% B:0.62%)
46.05% (G:10.17% B:0.38%)
Conf: ± 0.008 (+0.163...+0.179)
Duration: 1 hour 28 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 52 (subsequent cube action)

Wiggins implies that if White comes in with just one checker on the 3pt, White can take Black’s double. However, the XG rollout says that it is a drop:

Analyzed in Rollout
No Double
  Player Winning Chances: 68.13% (G: 34.84% B: 0.61%)
  Opponent Winning Chances: 31.87% (G: 8.61% B: 0.33%)
Double/Take
  Player Winning Chances: 68.21% (G: 37.68% B: 0.60%)
  Opponent Winning Chances: 31.79% (G: 9.23% B: 0.43%)
 
Cubeless Equities
No Double:+0.363
Double:+1.301
 
Cubeful Equities
No Double:+0.678 (-0.322)
Double/Take:+1.061 (+0.061)
Double/Drop:+1.000
 
Best Cube action: Double / Drop
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.005 (+0.674...+0.683)
Confidence Double: ± 0.008 (+1.053...+1.069)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 26 minutes 52 seconds


Similarly, Wiggins implies that if White rolls 5-3 and enters both checkers, then Black does not have a double. However, the XG rollout says that Black does have a double:

Analyzed in Rollout
No Double
  Player Winning Chances: 61.56% (G: 26.03% B: 0.53%)
  Opponent Winning Chances: 38.44% (G: 10.85% B: 0.41%)
Double/Take
  Player Winning Chances: 61.76% (G: 27.64% B: 0.53%)
  Opponent Winning Chances: 38.24% (G: 11.46% B: 0.53%)
 
Cubeless Equities
No Double:+0.231
Double:+0.794
 
Cubeful Equities
No Double:+0.460 (-0.052)
Double/Take:+0.512
Double/Drop:+1.000 (+0.488)
 
Best Cube action: Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.006 (+0.453...+0.466)
Confidence Double: ± 0.009 (+0.503...+0.521)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 1 hour 35 minutes


Position 55

Slotting with 6/5 comes in second place in the XG rollout but Wiggins does not mention it as a candidate.

1.Rollout1Bar/20 24/23eq: -0.215
Player:
Opponent:
45.19% (G:11.43% B:0.51%)
54.81% (G:16.18% B:0.73%)
Conf: ± 0.008 (-0.223...-0.207)
Duration: 2 hours 22 minutes
2.Rollout1Bar/20 6/5eq: -0.240 (-0.025)
Player:
Opponent:
45.62% (G:11.91% B:0.64%)
54.38% (G:19.26% B:1.22%)
Conf: ± 0.009 (-0.249...-0.231)
Duration: 1 hour 49 minutes
3.Rollout1Bar/20 11/10eq: -0.252 (-0.037)
Player:
Opponent:
44.37% (G:11.32% B:0.55%)
55.63% (G:16.82% B:0.85%)
Conf: ± 0.008 (-0.260...-0.244)
Duration: 2 hours 25 minutes
4.Rollout1Bar/24 13/8eq: -0.291 (-0.076)
Player:
Opponent:
43.13% (G:12.18% B:0.57%)
56.87% (G:17.18% B:1.00%)
Conf: ± 0.008 (-0.299...-0.283)
Duration: 3 hours 13 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 59 (variant)

This is a rollout of the variant position in which White’s 6pt spare has been moved forward one pip to make her 5pt. Wiggins says that in this variant, 10/6 8/3* would be correct, but XG still prefers the double hit.

1.Rollout18/3* 5/1* eq: +0.368
Player:
Opponent:
61.74% (G:38.94% B:1.72%)
38.26% (G:10.21% B:0.59%)
Conf: ± 0.007 (+0.361...+0.375)
Duration: 1 hour 07 minutes
2.Rollout122/18 8/3* eq: +0.339 (-0.029)
Player:
Opponent:
60.69% (G:35.59% B:2.51%)
39.31% (G:7.83% B:0.39%)
Conf: ± 0.006 (+0.333...+0.345)
Duration: 1 hour 02 minutes
3.Rollout122/13eq: +0.337 (-0.031)
Player:
Opponent:
61.06% (G:32.84% B:1.80%)
38.94% (G:6.11% B:0.24%)
Conf: ± 0.006 (+0.331...+0.343)
Duration: 1 hour 08 minutes
4.Rollout110/1* eq: +0.335 (-0.033)
Player:
Opponent:
60.67% (G:36.21% B:1.40%)
39.33% (G:8.36% B:0.37%)
Conf: ± 0.006 (+0.329...+0.341)
Duration: 1 hour 04 minutes
5.Rollout110/6 8/3* eq: +0.332 (-0.036)
Player:
Opponent:
59.85% (G:37.30% B:2.66%)
40.15% (G:8.28% B:0.43%)
Conf: ± 0.006 (+0.326...+0.338)
Duration: 57 minutes 29 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 60

The XG rollout seems to slightly favor hitting over anchoring.

1.Rollout124/21 8/7* eq: -0.077
Player:
Opponent:
46.35% (G:19.21% B:0.87%)
53.65% (G:16.31% B:1.21%)
Conf: ± 0.008 (-0.085...-0.069)
Duration: 55 minutes 32 seconds
2.Rollout124/21 22/21eq: -0.092 (-0.014)
Player:
Opponent:
46.40% (G:13.11% B:0.31%)
53.60% (G:9.05% B:0.39%)
Conf: ± 0.007 (-0.099...-0.085)
Duration: 1 hour 05 minutes
3.Rollout18/7* 7/4eq: -0.144 (-0.067)
Player:
Opponent:
44.22% (G:20.04% B:0.82%)
55.78% (G:15.99% B:1.00%)
Conf: ± 0.008 (-0.152...-0.136)
Duration: 54 minutes 10 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 72

XG prefers making the 5pt to the pick-and-pass play.

1.Rollout19/5 8/5eq: -0.339
Player:
Opponent:
40.54% (G:6.90% B:0.21%)
59.46% (G:9.11% B:0.34%)
Conf: ± 0.006 (-0.345...-0.333)
Duration: 1 hour 22 minutes
2.Rollout118/15* 15/11eq: -0.367 (-0.028)
Player:
Opponent:
41.69% (G:10.39% B:0.47%)
58.31% (G:17.42% B:0.94%)
Conf: ± 0.008 (-0.375...-0.359)
Duration: 1 hour 32 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 80

XG demotes Jellyfish’s choice to third place, and thinks the non-hitting 24/18 10/6 is a top contender.

1.Rollout118/14 18/12* eq: +0.598
Player:
Opponent:
64.06% (G:19.87% B:0.82%)
35.94% (G:9.21% B:0.72%)
Conf: ± 0.007 (+0.591...+0.605)
Duration: 36 minutes 37 seconds
2.Rollout124/18 10/6eq: +0.594 (-0.004)
Player:
Opponent:
65.85% (G:9.67% B:0.28%)
34.15% (G:6.27% B:0.23%)
Conf: ± 0.006 (+0.588...+0.600)
Duration: 44 minutes 27 seconds
3.Rollout124/20 18/12* eq: +0.560 (-0.038)
Player:
Opponent:
62.82% (G:20.95% B:1.01%)
37.18% (G:11.88% B:1.12%)
Conf: ± 0.007 (+0.553...+0.567)
Duration: 29 minutes 49 seconds
4.Rollout218/12* 10/6eq: +0.468 (-0.130)
Player:
Opponent:
60.92% (G:20.80% B:0.94%)
39.08% (G:10.28% B:0.60%)
Conf: ± 0.014 (+0.454...+0.482)
Duration: 8 minutes 39 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

2 1296 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 84

XG agrees that 24/22 24/21 and 24/22 8/5 and 24/21 9/7 are close, but it has a definite preference for 24/22 24/21.

1.Rollout124/22 24/21eq: +0.179
Player:
Opponent:
62.02% (G:19.14% B:1.18%)
37.98% (G:11.55% B:0.51%)
Conf.: ± 0.005 (+0.174...+0.184) - [100.0%]
Duration: 47 minutes 10 seconds
2.Rollout124/22 8/5eq: +0.163 (-0.016)
Player:
Opponent:
61.43% (G:19.02% B:1.11%)
38.57% (G:11.34% B:0.48%)
Conf.: ± 0.005 (+0.158...+0.168) - [0.0%]
Duration: 44 minutes 12 seconds
3.Rollout124/21 9/7eq: +0.162 (-0.016)
Player:
Opponent:
61.18% (G:19.94% B:1.19%)
38.82% (G:11.66% B:0.56%)
Conf.: ± 0.005 (+0.157...+0.168) - [0.0%]
Duration: 46 minutes 17 seconds
4.Rollout124/22 9/6eq: +0.142 (-0.037)
Player:
Opponent:
60.85% (G:18.03% B:1.03%)
39.15% (G:11.15% B:0.40%)
Conf.: ± 0.005 (+0.137...+0.147) - [0.0%]
Duration: 38 minutes 04 seconds
5.Rollout124/21 6/4eq: +0.139 (-0.040)
Player:
Opponent:
60.85% (G:20.47% B:1.29%)
39.15% (G:13.37% B:0.92%)
Conf.: ± 0.006 (+0.133...+0.145) - [0.0%]
Duration: 48 minutes 31 seconds
6.Rollout124/21 8/6eq: +0.118 (-0.061)
Player:
Opponent:
59.91% (G:18.95% B:1.10%)
40.09% (G:12.06% B:0.51%)
Conf.: ± 0.005 (+0.113...+0.123) - [0.0%]
Duration: 43 minutes 23 seconds
7.Rollout19/4eq: +0.095 (-0.084)
Player:
Opponent:
59.18% (G:18.40% B:1.01%)
40.82% (G:11.90% B:0.59%)
Conf.: ± 0.006 (+0.090...+0.101) - [0.0%]
Duration: 41 minutes 26 seconds
8.Rollout124/22 13/10eq: +0.088 (-0.090)
Player:
Opponent:
59.03% (G:19.54% B:1.32%)
40.97% (G:13.26% B:1.07%)
Conf.: ± 0.005 (+0.083...+0.093) - [0.0%]
Duration: 44 minutes 25 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 85

After Black closes his board, he has an immediate redouble, which Wiggins says White can take. The XG rollout says that White’s decision is right on the take/drop borderline.

Analyzed in Rollout
No Double
  Player Winning Chances: 71.68% (G: 18.63% B: 0.04%)
  Opponent Winning Chances: 28.32% (G: 3.32% B: 0.12%)
Double/Take
  Player Winning Chances: 71.92% (G: 19.79% B: 0.04%)
  Opponent Winning Chances: 28.08% (G: 3.47% B: 0.12%)
 
Cubeless Equities
No Redouble:+0.586
Redouble:+1.202
 
Cubeful Equities
No Redouble:+0.819 (-0.174)
Redouble/Take:+0.993
Redouble/Drop:+1.000 (+0.007)
 
Best Cube action: Redouble / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Redouble: ± 0.002 (+0.817...+0.822)
Confidence Redouble: ± 0.005 (+0.987...+0.998)
 
Double Decision confidence: 100.0%
Take Decision confidence: 99.5%
 
Duration: 15 minutes 23 seconds


Position 86

To trick XG into rolling this position out, I put Black’s two rearmost checkers on the bar, moved White’s checker on the bar to Black’s 17pt, and gave Black a roll of 4-4. XG thinks that 13/9 is only slightly better, and not “much better,” than 21/17.

1.Rollout1Bar/21 Bar/17* 13/9eq: +0.557
Player:
Opponent:
70.81% (G:29.13% B:3.21%)
29.19% (G:7.24% B:0.18%)
Conf.: ± 0.006 (+0.551...+0.563) - [98.1%]
Duration: 58 minutes 19 seconds
2.Rollout1Bar/17*(2) eq: +0.549 (-0.008)
Player:
Opponent:
71.74% (G:26.47% B:2.33%)
28.26% (G:6.84% B:0.18%)
Conf.: ± 0.005 (+0.544...+0.554) - [1.9%]
Duration: 54 minutes 48 seconds
3.Rollout1Bar/21 Bar/17* 17/13eq: +0.481 (-0.076)
Player:
Opponent:
68.81% (G:27.76% B:2.98%)
31.19% (G:8.12% B:0.19%)
Conf.: ± 0.005 (+0.476...+0.487) - [0.0%]
Duration: 55 minutes 55 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 89

XG favors 8/3 7/1, the move that Wiggins suspects “most good players would choose,” and demotes Jellyfish’s 22/16 8/3 to 6th place. Note: There are several other uninteresting plays that come out ahead of 22/16 14/9 but that are not displayed here.

1.Rollout18/3 7/1eq: -0.286
Player:
Opponent:
32.26% (G:4.40% B:0.11%)
67.74% (G:5.66% B:0.10%)
Conf: ± 0.003 (-0.289...-0.283)
Duration: 18 minutes 00 second
2.Rollout114/3eq: -0.328 (-0.042)
Player:
Opponent:
30.53% (G:2.70% B:0.04%)
69.47% (G:4.04% B:0.07%)
Conf: ± 0.002 (-0.330...-0.326)
Duration: 15 minutes 32 seconds
3.Rollout114/9 7/1eq: -0.346 (-0.060)
Player:
Opponent:
29.86% (G:3.09% B:0.06%)
70.14% (G:4.51% B:0.23%)
Conf: ± 0.002 (-0.348...-0.344)
Duration: 15 minutes 03 seconds
4.Rollout17/1 6/1eq: -0.351 (-0.065)
Player:
Opponent:
30.22% (G:4.41% B:0.11%)
69.78% (G:8.32% B:0.36%)
Conf: ± 0.003 (-0.354...-0.348)
Duration: 16 minutes 59 seconds
5.Rollout114/9 8/2eq: -0.360 (-0.075)
Player:
Opponent:
28.96% (G:2.20% B:0.05%)
71.04% (G:3.96% B:0.09%)
Conf: ± 0.002 (-0.362...-0.358)
Duration: 14 minutes 50 seconds
6.Rollout122/16 8/3eq: -0.364 (-0.078)
Player:
Opponent:
35.55% (G:9.26% B:0.28%)
64.45% (G:22.79% B:0.65%)
Conf: ± 0.003 (-0.367...-0.361)
Duration: 22 minutes 56 seconds
7.Rollout114/8 7/2eq: -0.370 (-0.084)
Player:
Opponent:
28.78% (G:2.51% B:0.06%)
71.22% (G:4.80% B:0.12%)
Conf: ± 0.002 (-0.372...-0.368)
Duration: 13 minutes 26 seconds
8.Rollout122/16 14/9eq: -0.460 (-0.174)
Player:
Opponent:
31.73% (G:7.92% B:0.25%)
68.27% (G:23.47% B:0.73%)
Conf: ± 0.003 (-0.463...-0.457)
Duration: 20 minutes 26 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 92

XG prefers making the 3pt to hitting with 24/18* 13/10.

1.Rollout19/3 6/3eq: +0.459
Player:
Opponent:
60.89% (G:20.15% B:1.47%)
39.11% (G:19.13% B:2.94%)
Conf: ± 0.008 (+0.451...+0.467)
Duration: 50 minutes 13 seconds
2.Rollout124/18* 13/10eq: +0.420 (-0.039)
Player:
Opponent:
58.97% (G:21.28% B:1.68%)
41.03% (G:21.76% B:2.25%)
Conf: ± 0.009 (+0.411...+0.429)
Duration: 58 minutes 29 seconds
3.Rollout224/18* 10/7eq: +0.384 (-0.075)
Player:
Opponent:
57.92% (G:20.25% B:1.54%)
42.08% (G:21.16% B:1.54%)
Conf: ± 0.015 (+0.369...+0.399)
Duration: 15 minutes 05 seconds
4.Rollout224/18* 18/15eq: +0.366 (-0.093)
Player:
Opponent:
57.53% (G:20.96% B:1.69%)
42.47% (G:23.54% B:2.39%)
Conf: ± 0.017 (+0.349...+0.383)
Duration: 14 minutes 40 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

2 1296 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 93 (subsequent cube action)

Wiggins says that anchoring will provoke a double from White whereas the hit will not. The XG rollouts indicate that both doubling decisions are close, but that if anything, it is the other way around. If the XG rollouts are correct, then we have here an example of a cube provocation play, where the play that provokes a cube is to be preferred over the play that does not provoke the cube.

White’s cube decision after Black hits on the 18pt:

Analyzed in Rollout
No Double
  Player Winning Chances: 61.47% (G: 24.69% B: 0.89%)
  Opponent Winning Chances: 38.53% (G: 8.85% B: 0.54%)
Double/Take
  Player Winning Chances: 61.40% (G: 26.60% B: 0.94%)
  Opponent Winning Chances: 38.60% (G: 9.40% B: 0.60%)
 
Cubeless Equities
No Double:+0.229
Double:+0.807
 
Cubeful Equities
No Double:+0.509 (-0.004)
Double/Take:+0.513
Double/Drop:+1.000 (+0.487)
 
Best Cube action: Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.007 (+0.503...+0.516)
Confidence Double: ± 0.010 (+0.504...+0.523)
 
Double Decision confidence: 75.7%
Take Decision confidence: 100.0%
 
Duration: 1 hour 25 minutes


White’s cube decision after Black anchors:

Analyzed in Rollout
No Double
  Player Winning Chances: 70.02% (G: 11.52% B: 0.27%)
  Opponent Winning Chances: 29.98% (G: 3.98% B: 0.15%)
Double/Take
  Player Winning Chances: 70.06% (G: 11.55% B: 0.28%)
  Opponent Winning Chances: 29.94% (G: 4.07% B: 0.16%)
 
Cubeless Equities
No Double:+0.400
Double:+0.954
 
Cubeful Equities
No Double:+0.766
Double/Take:+0.753 (-0.013)
Double/Drop:+1.000 (+0.234)
 
Best Cube action: No Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.007 (+0.759...+0.773)
Confidence Double: ± 0.007 (+0.745...+0.760)
 
Double Decision confidence: 99.6%
Take Decision confidence: 100.0%
 
Duration: 1 hour 34 minutes


Position 94 (subsequent cube action)

Wiggins implies that after Black’s play, if White enters a checker, then White will be able to take Black’s double. However, here is the XG rollout of Black’s cube decision after White enters one checker on Black’s 4pt:

Analyzed in Rollout
No Double
  Player Winning Chances: 65.28% (G: 48.46% B: 0.44%)
  Opponent Winning Chances: 34.72% (G: 7.71% B: 0.43%)
Double/Take
  Player Winning Chances: 66.63% (G: 50.77% B: 0.40%)
  Opponent Winning Chances: 33.37% (G: 8.35% B: 0.58%)
 
Cubeless Equities
No Double:+0.306
Double:+1.510
 
Cubeful Equities
No Double:+0.712 (-0.288)
Double/Take:+1.234 (+0.234)
Double/Drop:+1.000
 
Best Cube action: Double / Drop
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.006 (+0.706...+0.718)
Confidence Double: ± 0.010 (+1.224...+1.245)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 47 minutes 07 seconds


Position 100

XG favors hitting with 8/7* over 6/5.

1.Rollout1Bar/21 8/7* eq: -0.629
Player:
Opponent:
38.77% (G:8.88% B:0.46%)
61.23% (G:29.74% B:4.41%)
Conf: ± 0.012 (-0.641...-0.617)
Duration: 1 hour 05 minutes
2.Rollout1Bar/21 6/5eq: -0.675 (-0.046)
Player:
Opponent:
35.42% (G:7.92% B:0.35%)
64.58% (G:24.64% B:2.32%)
Conf: ± 0.010 (-0.685...-0.665)
Duration: 58 minutes 07 seconds
3.Rollout1Bar/21 24/23eq: -0.789 (-0.160)
Player:
Opponent:
34.68% (G:7.95% B:0.35%)
65.32% (G:29.18% B:1.67%)
Conf: ± 0.010 (-0.799...-0.779)
Duration: 52 minutes 18 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Wiggins says that 6/5 “staves off White’s double” but the XG rollout says that it may be a marginal double:

Analyzed in Rollout
No Double
  Player Winning Chances: 64.60% (G: 24.44% B: 2.19%)
  Opponent Winning Chances: 35.40% (G: 7.85% B: 0.34%)
Double/Take
  Player Winning Chances: 64.67% (G: 24.60% B: 2.31%)
  Opponent Winning Chances: 35.33% (G: 7.96% B: 0.36%)
 
Cubeless Equities
No Double:+0.292
Double:+0.959
 
Cubeful Equities
No Double:+0.667 (-0.007)
Double/Take:+0.674
Double/Drop:+1.000 (+0.326)
 
Best Cube action: Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.008 (+0.659...+0.674)
Confidence Double: ± 0.010 (+0.663...+0.684)
 
Double Decision confidence: 85.7%
Take Decision confidence: 100.0%
 
Duration: 1 hour 43 minutes


For comparison, here is the rollout for White’s cube action after 8/7*:

Analyzed in Rollout
No Double
  Player Winning Chances: 61.40% (G: 29.44% B: 3.95%)
  Opponent Winning Chances: 38.60% (G: 8.85% B: 0.41%)
Double/Take
  Player Winning Chances: 61.36% (G: 29.69% B: 4.29%)
  Opponent Winning Chances: 38.64% (G: 8.91% B: 0.45%)
 
Cubeless Equities
No Double:+0.228
Double:+0.947
 
Cubeful Equities
No Double:+0.598 (-0.026)
Double/Take:+0.624
Double/Drop:+1.000 (+0.376)
 
Best Cube action: Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.009 (+0.589...+0.606)
Confidence Double: ± 0.012 (+0.611...+0.636)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 1 hour 58 minutes


Position 102

Wiggins accepts Jellyfish’s verdict that 18/9 and 13/4 are tied, but XG clearly favors 18/9, and it even ranks 18/15 13/7 (which Wiggins does not mention as a candidate) ahead of 13/4.

1.Rollout118/9eq: +0.368
Player:
Opponent:
67.26% (G:20.12% B:0.84%)
32.74% (G:6.00% B:0.21%)
Conf: ± 0.010 (+0.358...+0.378)
Duration: 13 minutes 28 seconds
2.Rollout118/15 13/7eq: +0.339 (-0.029)
Player:
Opponent:
66.45% (G:19.98% B:0.79%)
33.55% (G:6.54% B:0.24%)
Conf: ± 0.010 (+0.329...+0.349)
Duration: 12 minutes 55 seconds
3.Rollout113/4eq: +0.324 (-0.044)
Player:
Opponent:
66.21% (G:19.60% B:0.58%)
33.79% (G:6.17% B:0.24%)
Conf: ± 0.010 (+0.314...+0.334)
Duration: 12 minutes 43 seconds
 
1 1296 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 105

There is only a small discrepancy here, but XG thinks that the break-even point occurs when White’s outfield blot is shifted forwards two pips, to White’s 8pt.

Rollout of original position:

1.Rollout16/4 6/3eq: +0.914
Player:
Opponent:
92.00% (G:9.36% B:0.23%)
8.00% (G:0.00% B:0.00%)
Conf: ± 0.001 (+0.913...+0.915)
Duration: 4 minutes 18 seconds
2.Rollout13/0ff 2/0ffeq: +0.900 (-0.014)
Player:
Opponent:
88.93% (G:15.14% B:0.49%)
11.07% (G:0.00% B:0.00%)
Conf: ± 0.001 (+0.899...+0.901)
Duration: 4 minutes 47 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Rollout of variant in which White’s 10pt checker is moved to her 8pt:

1.Rollout16/4 6/3eq: +0.920
Player:
Opponent:
92.84% (G:8.10% B:0.17%)
7.16% (G:0.00% B:0.00%)
Conf: ± 0.001 (+0.919...+0.921)
Duration: 4 minutes 09 seconds
2.Rollout13/0ff 2/0ffeq: +0.919 (-0.001)
Player:
Opponent:
89.95% (G:14.74% B:0.45%)
10.05% (G:0.00% B:0.00%)
Conf: ± 0.002 (+0.917...+0.921)
Duration: 4 minutes 26 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 109

Wiggins does not mention 13/7 8/4*, which the XG rollout thinks is a contender for first place.

1.Rollout115/9 8/4* eq: -0.474
Player:
Opponent:
37.90% (G:11.54% B:0.22%)
62.10% (G:17.32% B:1.10%)
Conf: ± 0.007 (-0.481...-0.467)
Duration: 1 hour 03 minutes
2.Rollout113/7 8/4* eq: -0.474
Player:
Opponent:
38.20% (G:12.04% B:0.27%)
61.80% (G:19.61% B:1.52%)
Conf: ± 0.008 (-0.482...-0.466)
Duration: 1 hour 04 minutes
3.Rollout115/9 13/9eq: -0.578 (-0.103)
Player:
Opponent:
34.57% (G:8.84% B:0.19%)
65.43% (G:14.45% B:0.75%)
Conf: ± 0.007 (-0.585...-0.571)
Duration: 1 hour 02 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 110

No disagreement here about the top play, but XG thinks the second-best play is bar/22 8/7, which Wiggins does not mention as a candidate play at all.

1.Rollout1Bar/22 24/23eq: -0.445
Player:
Opponent:
39.29% (G:10.08% B:0.43%)
60.71% (G:17.06% B:0.97%)
Conf.: ± 0.009 (-0.454...-0.436) - [100.0%]
Duration: 7 hours 06 minutes
2.Rollout1Bar/22 8/7eq: -0.497 (-0.052)
Player:
Opponent:
37.94% (G:10.04% B:0.45%)
62.06% (G:18.07% B:1.23%)
Conf.: ± 0.008 (-0.505...-0.489) - [0.0%]
Duration: 6 hours 53 minutes
3.Rollout1Bar/21eq: -0.512 (-0.067)
Player:
Opponent:
37.80% (G:9.66% B:0.40%)
62.20% (G:18.60% B:1.36%)
Conf.: ± 0.008 (-0.520...-0.504) - [0.0%]
Duration: 6 hours 48 minutes
4.Rollout1Bar/22 6/5eq: -0.541 (-0.096)
Player:
Opponent:
38.48% (G:9.70% B:0.47%)
61.52% (G:21.67% B:1.91%)
Conf.: ± 0.009 (-0.550...-0.531) - [0.0%]
Duration: 7 hours 06 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller


Position 114 (variant)

Wiggins says that after 6/4*(2) 3/1*(2), “White won’t be able to take the cube that is coming next turn unless he enters with 5-5, 3-3, or 2-2.” However, here for example is an XG rollout of Black’s cube decision if White rolls 3-2 and enters with bar/23 bar/22:

Analyzed in Rollout
No Double
  Player Winning Chances: 60.78% (G: 30.68% B: 1.82%)
  Opponent Winning Chances: 39.22% (G: 10.09% B: 0.54%)
Double/Take
  Player Winning Chances: 61.09% (G: 31.63% B: 2.30%)
  Opponent Winning Chances: 38.91% (G: 10.28% B: 0.54%)
 
Cubeless Equities
No Double:+0.216
Double:+0.906
 
Cubeful Equities
No Double:+0.520 (-0.073)
Double/Take:+0.593
Double/Drop:+1.000 (+0.407)
 
Best Cube action: Double / Take
 
Rollout details
5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.008 (+0.512...+0.527)
Confidence Double: ± 0.011 (+0.582...+0.604)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 1 hour 45 minutes


Position 115 (cube decision before roll)

The XG rollout below is of Black’s cube decision before the roll that Wiggins discusses. According to XG, Black should have doubled before rolling.

Analyzed in Rollout
No Double
  Player Winning Chances: 61.22% (G: 34.54% B: 1.78%)
  Opponent Winning Chances: 38.78% (G: 9.63% B: 0.59%)
Double/Take
  Player Winning Chances: 61.58% (G: 36.80% B: 1.72%)
  Opponent Winning Chances: 38.42% (G: 10.16% B: 0.64%)
 
Cubeless Equities
No Double:+0.224
Double:+1.017
 
Cubeful Equities
No Double:+0.605 (-0.103)
Double/Take:+0.708
Double/Drop:+1.000 (+0.292)
 
Best Cube action: Double / Take
 
Rollout details
1296 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller
 
Confidence No Double: ± 0.010 (+0.594...+0.615)
Confidence Double: ± 0.017 (+0.691...+0.725)
 
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
 
Duration: 16 minutes 10 seconds


Position 118

XG prefers 6/2* to 23/22 8/5, and also thinks that 8/5 6/5 is a serious candidate. Wiggins does not mention 8/5 6/5.

1.Rollout16/2* eq: -0.251
Player:
Opponent:
35.61% (G:12.54% B:1.02%)
64.39% (G:22.03% B:1.35%)
Conf: ± 0.006 (-0.257...-0.245)
Duration: 55 minutes 16 seconds
2.Rollout18/5 6/5eq: -0.255 (-0.005)
Player:
Opponent:
34.44% (G:12.35% B:0.71%)
65.56% (G:19.21% B:1.03%)
Conf: ± 0.006 (-0.261...-0.249)
Duration: 47 minutes 06 seconds
3.Rollout123/22 8/5eq: -0.272 (-0.021)
Player:
Opponent:
36.59% (G:13.67% B:1.16%)
63.41% (G:27.71% B:1.21%)
Conf: ± 0.006 (-0.278...-0.266)
Duration: 44 minutes 37 seconds
4.Rollout113/10 6/5eq: -0.290 (-0.039)
Player:
Opponent:
33.56% (G:11.39% B:0.68%)
66.44% (G:19.75% B:1.13%)
Conf: ± 0.006 (-0.296...-0.284)
Duration: 46 minutes 46 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 121

Not much disagreement here between the bots, except that XG puts 24/20 10/5 (a candidate that is not mentioned by Wiggins) in second place, ahead of 10/1 and 10/6 7/2.

1.Rollout124/15eq: -0.802
Player:
Opponent:
12.56% (G:0.01% B:0.00%)
87.44% (G:8.95% B:0.05%)
Conf: ± 0.001 (-0.803...-0.801)
Duration: 8 minutes 07 seconds
2.Rollout124/20 10/5eq: -0.824 (-0.021)
Player:
Opponent:
12.41% (G:0.00% B:0.00%)
87.59% (G:11.19% B:0.12%)
Conf: ± 0.001 (-0.825...-0.823)
Duration: 6 minutes 11 seconds
3.Rollout110/1eq: -0.862 (-0.060)
Player:
Opponent:
10.75% (G:0.00% B:0.00%)
89.25% (G:10.73% B:0.26%)
Conf: ± 0.001 (-0.863...-0.861)
Duration: 5 minutes 58 seconds
4.Rollout110/6 7/2eq: -0.870 (-0.068)
Player:
Opponent:
10.09% (G:0.00% B:0.00%)
89.91% (G:10.39% B:0.25%)
Conf: ± 0.001 (-0.871...-0.869)
Duration: 5 minutes 14 seconds
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller


Position 128

Again, not much to note here other than that Wiggins fails to mention 24/20 13/7 as a candidate.

1.Rollout124/14eq: -0.026
Player:
Opponent:
50.11% (G:12.26% B:0.61%)
49.89% (G:15.49% B:0.49%)
Conf: ± 0.007 (-0.033...-0.019)
Duration: 1 hour 17 minutes
2.Rollout124/20 13/7eq: -0.066 (-0.040)
Player:
Opponent:
48.74% (G:13.92% B:0.75%)
51.26% (G:16.36% B:0.62%)
Conf: ± 0.008 (-0.074...-0.058)
Duration: 1 hour 14 minutes
3.Rollout18/2* 6/2eq: -0.071 (-0.045)
Player:
Opponent:
47.38% (G:16.29% B:0.73%)
52.62% (G:14.86% B:0.79%)
Conf: ± 0.008 (-0.079...-0.063)
Duration: 1 hour 07 minutes
 
1 5184 Games rolled with Variance Reduction.
Moves: 3 ply, cube decisions: XG Roller

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