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Rockwell Teaches Mochy

Posted By: David Rockwell
Date: Thursday, 23 January 2014, at 10:27 p.m.

In Response To: Rockwell Teaches Mochy (Stick)

The fundamental for playing an early game 33 is to first ask if there is special reason to make the 21 point anchor. The primary reason to anchor is to prevent the opponent from making the point on the next roll. I always use the pair 52D-33 and 53D-33 (RO below) to illustrate the concept. After 52D, 33A {attack 8-5(2), 6-3(2)} is correct. After 53D, 33C {Cross 24-21(2), 8-5(2)} is correct. The builder on the 10 point makes the difference. Facing three builders for the 21, the anchor is required. Facing two, it is not. The secondary reason to play 24-21(2) is to get the back checkers moving when opponent has started to make a prime. The response 31P-33 is best played 33B {Both 24-21(2), 13-10(2)}. If neither of these two conditions apply defense is not urgent and 33A is usually best. Two exceptions to this rule on the second roll are 65R-33 and 64P-33; the two positions relevant to this post. The correct move for both of these is 33B even though neither of the fundamental reasons for making the anchor apply. We need to keep searching.

So, why is it correct to play 33B after an opening 65R and yet it correct to play 33A on the third move; 42P-65R-33? What has changed? I will pause to see if anyone can spot the key difference.

 White is Player 2 score: 0 pip: 160 Unlimited GameJacoby Beaver pip: 167 score: 0 Blue is Player 1
XGID=-b----E-C---cEa--d-e----B-:0:0:1:33:0:0:3:0:10
Blue to play 33

1.Rollout18/5(2) 6/3(2)eq: +0.2983
 Player:Opponent: 56.18% (G:20.30% B:1.12%)43.82% (G:12.53% B:0.70%) Conf.: ±0.0040 (+0.2944...+0.3023) - [100.0%]Duration: 6 hours 39 minutes
2.Rollout124/21(2) 8/5(2)eq: +0.2683 (-0.0300)
 Player:Opponent: 55.47% (G:16.88% B:0.63%)44.53% (G:9.30% B:0.36%) Conf.: ±0.0037 (+0.2646...+0.2720) - [0.0%]Duration: 7 hours 53 minutes
3.Rollout224/21(2) 13/10(2)eq: +0.2633 (-0.0351)
 Player:Opponent: 55.75% (G:15.17% B:0.59%)44.25% (G:9.20% B:0.34%) Conf.: ±0.0041 (+0.2592...+0.2673) - [0.0%]Duration: 5 hours 29 minutes
4.Rollout324/21(2) 6/3(2)eq: +0.2557 (-0.0427)
 Player:Opponent: 55.43% (G:15.39% B:0.66%)44.57% (G:9.14% B:0.34%) Conf.: ±0.0051 (+0.2505...+0.2608) - [0.0%]Duration: 2 hours 29 minutes
1 20736 Games rolled with Variance Reduction.
Dice Seed: 6661562
Moves and cube decisions: 3-ply

2 15552 Games rolled with Variance Reduction.
Dice Seed: 6661562
Moves and cube decisions: 3-ply

3 10368 Games rolled with Variance Reduction.
Dice Seed: 6661562
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.10

 White is Player 2 score: 0 pip: 159 Unlimited Game pip: 167 score: 0 Blue is Player 1
XGID=-b----E-C---cE-a-d-e----B-:0:0:1:33:0:0:0:0:10
Blue to play 33

1.Rollout124/21(2) 8/5(2)eq: +0.2905
 Player:Opponent: 55.91% (G:17.55% B:0.61%)44.09% (G:9.36% B:0.38%) Conf.: ±0.0079 (+0.2826...+0.2983) - [98.3%]Duration: 42 minutes 40 seconds
2.Rollout18/5(2) 6/3(2)eq: +0.2780 (-0.0125)
 Player:Opponent: 56.07% (G:19.81% B:1.13%)43.93% (G:13.08% B:0.70%) Conf.: ±0.0075 (+0.2704...+0.2855) - [1.2%]Duration: 36 minutes 13 seconds
3.Rollout124/21(2) 6/3(2)eq: +0.2776 (-0.0129)
 Player:Opponent: 56.02% (G:15.77% B:0.61%)43.98% (G:8.93% B:0.35%) Conf.: ±0.0062 (+0.2713...+0.2838) - [0.5%]Duration: 42 minutes 39 seconds
4.Rollout124/21(2) 13/10(2)eq: +0.2454 (-0.0451)
 Player:Opponent: 55.38% (G:15.50% B:0.59%)44.62% (G:9.48% B:0.36%) Conf.: ±0.0067 (+0.2387...+0.2521) - [0.0%]Duration: 45 minutes 36 seconds
1 5184 Games rolled with Variance Reduction.
Dice Seed: 7691003
Moves and cube decisions: 3-ply

eXtreme Gammon Version: 2.10

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