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Black to play 11 — You have to take it in stages.
08-12-2012
, 02:47 AM
Here we are in the August doldrums. Many are away on vacation. Others are outside making some hay in the sunshine. TwoPlusTwo has a tendency to slow down around this time of year.
In order to help spark some activity, I am posting the following problem. I already know the answer, so I am posing this as an entertainment for you. I have already written up my explanation. I hope to post it in a couple of days, along with my rollout.
This is not a difficult choice, but you have to take it in stages.
In order to help spark some activity, I am posting the following problem. I already know the answer, so I am posing this as an entertainment for you. I have already written up my explanation. I hope to post it in a couple of days, along with my rollout.
This is not a difficult choice, but you have to take it in stages.
08-16-2012
, 03:22 AM
White - Pips 124
Black - Pips 68
Black to Play 1-1
Black - Pips 68
Black to Play 1-1
Original Position — Anchor on 4pt
This is not a difficult choice, but you have to take it in stages.
- Ahead by miles in the race, there is no reason to block. Prepare to clear from the rear by switching points, and thereby fill the gap on the 8pt. That takes care of the first two aces.
- Decide whether to leave an odd checker on the 6pt. In many circumstances it is correct to “get even” on the two highest points, but not always. If 5 were a trouble number, then it would be worth the risk of exposing a blot when you roll high doublets in order to keep a playable spare on the 6pt. In this case, however, the trouble numbers are 1 and 4. Those are the numbers that are blocked when you try to clear the 8pt. So long as you have plenty of those, you can wait for a lucky number to clear the 8pt safely. A roll of 5 can be played by clearing either the 8pt or the 6pt. Play the third ace 6/5.
- Choose which lower-board point to break. Obviously, you are not going to leave a shot, so the 2pt or 3pt must be broken. Keeping all the playable 2s you can find is the key. Move 2/1.
White - Pips 126
Black - Pips 70
Black to Play 1-1
Black - Pips 70
Black to Play 1-1
Variant Position — Anchor on 3pt
The issue of trouble numbers is one of the most important, yet least understood, principles of bearing in. Kit Woolsey writes about it in a 2002 article entitled Bearing in Safely.
In the variant above, White’s anchor has been moved back to the 3pt. That means that 1 and 5 are now the trouble numbers for Blue when he goes to clear the 8pt. As the rollout confirms, he needs to keep his spare on the 6pt, so that he has a safe 5 he can play while he is waiting for a “lucky” roll that will let him clear the 8pt. Note that the play that was best in the original position has slipped into fourth place in this variant.
Thanks for reading. I hope you enjoyed this problem. Rollouts follow.
Rollout of Original Position
Code:
XGID=-BBBbDCb-B---------ccba-b-:1:-1:1:11:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
Pip count X: 68 O: 124 X-O: 0-0
Cube: 2, O own cube
X to play 11
1. Rollout¹ 9/8(2) 6/5 2/1 eq:+0.8031
Player: 87.65% (G:10.29% B:0.04%)
Opponent: 12.35% (G:0.49% B:0.01%)
Confidence: ±0.0021 (+0.8010..+0.8052) - [100.0%]
Duration: 10 minutes 05 seconds
2. Rollout¹ 9/8(2) 6/5 3/2 eq:+0.7932 (-0.0099)
Player: 87.12% (G:10.72% B:0.06%)
Opponent: 12.88% (G:0.66% B:0.02%)
Confidence: ±0.0023 (+0.7909..+0.7954) - [0.0%]
Duration: 9 minutes 37 seconds
3. Rollout¹ 9/8(2) 3/1 eq:+0.7917 (-0.0114)
Player: 87.14% (G:10.37% B:0.05%)
Opponent: 12.86% (G:0.59% B:0.02%)
Confidence: ±0.0021 (+0.7897..+0.7938) - [0.0%]
Duration: 9 minutes 15 seconds
4. Rollout¹ 9/8(2) 2/1(2) eq:+0.7807 (-0.0225)
Player: 86.54% (G:10.77% B:0.06%)
Opponent: 13.46% (G:0.53% B:0.01%)
Confidence: ±0.0021 (+0.7785..+0.7828) - [0.0%]
Duration: 8 minutes 57 seconds
5. Rollout¹ 9/8(2) 3/2(2) eq:+0.7635 (-0.0396)
Player: 86.24% (G:9.74% B:0.04%)
Opponent: 13.76% (G:0.64% B:0.02%)
Confidence: ±0.0021 (+0.7614..+0.7656) - [0.0%]
Duration: 9 minutes 36 seconds
¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 5974299
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2012-Aug-06
eXtreme Gammon Version: 2.03
Flashcard PositionID 000666.xgp
Rollout of Variant Position
Code:
XGID=-BBbBDCb-B---------ccba-b-:1:-1:1:11:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
Pip count X: 70 O: 126 X-O: 0-0
Cube: 2, O own cube
X to play 11
1. Rollout¹ 9/8(2) 5/4 2/1 eq:+0.7200
Player: 83.38% (G:11.92% B:0.12%)
Opponent: 16.62% (G:0.73% B:0.02%)
Confidence: ±0.0021 (+0.7179..+0.7221) - [100.0%]
Duration: 8 minutes 15 seconds
2. Rollout¹ 9/8(2) 6/4 eq:+0.7111 (-0.0089)
Player: 82.85% (G:13.01% B:0.15%)
Opponent: 17.15% (G:1.19% B:0.03%)
Confidence: ±0.0021 (+0.7090..+0.7132) - [0.0%]
Duration: 7 minutes 56 seconds
3. Rollout¹ 9/8(2) 5/4(2) eq:+0.7037 (-0.0163)
Player: 82.71% (G:12.08% B:0.11%)
Opponent: 17.29% (G:0.77% B:0.02%)
Confidence: ±0.0021 (+0.7016..+0.7058) - [0.0%]
Duration: 7 minutes 02 seconds
4. Rollout¹ 9/8(2) 6/5 2/1 eq:+0.6783 (-0.0416)
Player: 81.98% (G:11.65% B:0.11%)
Opponent: 18.02% (G:1.34% B:0.04%)
Confidence: ±0.0045 (+0.6739..+0.6828) - [0.0%]
Duration: 7 minutes 59 seconds
¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 79667159
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2012-Aug-15
eXtreme Gammon Version: 2.03
Flashcard PositionID 000672.xgp
08-16-2012
, 04:39 AM
08-16-2012
, 01:49 PM
Details matter a lot in such a geek game!
