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Open your mind
04-23-2015
, 05:46 PM
White - Pips 133
Black - Pips 168
Position 19. Black to Play 4-1
Unlimited game, no Jacoby, no beavers
XGID=--a---D-D---bD--Aebe--B---:0:0:1:41:0:0:0:0:10
This may look like two beginners have been building candlesticks, but this game has been well played so far. Both players have been rolling 5s, and to to cap it off, White just rolled a 66.
Over the board, I played 16/11, thinking that I did not want to be hit, and that the 11pt was the optimal destination for a checker in my outer board. That play is a near-whopper!
The blot on the 16pt is doing fine right where it is. It exerts pressure both on White’s midpoint and on the high points in Black’s outer board. White would have to break his midpoint to hit, something that might leave his outer board in a mess. Note also the connectivity. The 16pt is within direct range of Black’s anchor, so he can hit from there if it becomes desirable.
Thinking about game plans will help here. White has jumped out to a huge racing advantage, so Black does not want to play a running game. Anything that reduces contact, such as playing 16/11, will help White further his plans to run. Black needs to play a priming game or some sort of a tactical holding game.
The best 4, therefore, is to play down from the midpoint. After that, the ace could be played 16/15, but a better play is to slot the 5pt. It looks like that volunteers a double direct-shot, because both 3 and 4 hit, but White will not be anxious to break his midpoint. When Black’s slot is not hit, Black gains in the priming battle. When the slot is hit, Black will often be able to use that checker to good advantage in a holding game. A third checker back may give him the flexibility he needs to advance his anchor. Slotting is a two-way move that supports both a priming game and a holding game.
Here’s my 31k rollout.
Position 19. Rollout
This position is very sensitive to the location of Black’s anchor. Moving it forward just one pip is all it takes to make the safer 16/15 13/9 come out on top. Moving the anchor up to the 20pt gives that play an even larger edge. From either of those anchors, Black can already engineer a decent holding game. The “advantage” in having a slotted checker hit is much smaller. Note that 16/11 still fairs poorly in both of these variants.
White - Pips 133
Black - Pips 166
Position 19a. Black to Play 4-1
It is hard to find a variant where 16/11 is correct. The race needs to be much less lopsided. Moving a White checker from his 8pt back to the midpoint won’t do it. Moving two, makes it close. Any further change takes you so far away from the original that you are no longer comparing similar positions.
White - Pips 143
Black - Pips 168
Position 19b. Black to Play 4-1
Mike
Black - Pips 168
Position 19. Black to Play 4-1
Unlimited game, no Jacoby, no beavers
XGID=--a---D-D---bD--Aebe--B---:0:0:1:41:0:0:0:0:10
This may look like two beginners have been building candlesticks, but this game has been well played so far. Both players have been rolling 5s, and to to cap it off, White just rolled a 66.
- Black 52-split: 24/22, 13/8
- White 54-split: 24/20, 13/8
- Black 21-hit and anchor: 24/22, 6/5*
- White 51-up: bar/20*, 24/23
- Black 63-run: bar/16
- White 66-reverse split: 20/8, 13/7(2)
- Black 41 ?
Over the board, I played 16/11, thinking that I did not want to be hit, and that the 11pt was the optimal destination for a checker in my outer board. That play is a near-whopper!
The blot on the 16pt is doing fine right where it is. It exerts pressure both on White’s midpoint and on the high points in Black’s outer board. White would have to break his midpoint to hit, something that might leave his outer board in a mess. Note also the connectivity. The 16pt is within direct range of Black’s anchor, so he can hit from there if it becomes desirable.
Thinking about game plans will help here. White has jumped out to a huge racing advantage, so Black does not want to play a running game. Anything that reduces contact, such as playing 16/11, will help White further his plans to run. Black needs to play a priming game or some sort of a tactical holding game.
The best 4, therefore, is to play down from the midpoint. After that, the ace could be played 16/15, but a better play is to slot the 5pt. It looks like that volunteers a double direct-shot, because both 3 and 4 hit, but White will not be anxious to break his midpoint. When Black’s slot is not hit, Black gains in the priming battle. When the slot is hit, Black will often be able to use that checker to good advantage in a holding game. A third checker back may give him the flexibility he needs to advance his anchor. Slotting is a two-way move that supports both a priming game and a holding game.
Here’s my 31k rollout.
Position 19. Rollout
Code:
XGID=--a---D-D---bD--Aebe--B---:0:0:1:41:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
Pip count X: 168 O: 133 X-O: 0-0
Cube: 1
X to play 41
1. Rollout¹ 13/9 6/5 eq:-0.3488
Player: 43.20% (G:8.84% B:0.34%)
Opponent: 56.80% (G:18.89% B:0.79%)
Confidence: ±0.0035 (-0.3523..-0.3453) - [100.0%]
2. Rollout¹ 16/15 13/9 eq:-0.3603 (-0.0115)
Player: 41.73% (G:8.43% B:0.31%)
Opponent: 58.27% (G:15.63% B:0.59%)
Confidence: ±0.0031 (-0.3634..-0.3573) - [0.0%]
3. Rollout² 16/11 eq:-0.4388 (-0.0900)
Player: 38.93% (G:7.48% B:0.26%)
Opponent: 61.07% (G:12.74% B:0.42%)
Confidence: ±0.0068 (-0.4456..-0.4321) - [0.0%]
¹ 31104 Games rolled with Variance Reduction.
Dice Seed: 46439202
Moves: 3-ply, cube decisions: XG Roller
² 5184 Games rolled with Variance Reduction.
Dice Seed: 46439202
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2015-Apr-22
eXtreme Gammon Version: 2.10.199.2658
52S-54S-21X-51U-63R-66Z-41-n-tm.xgp
Posted at TwoPlusTwo.com as:
OpenYourMind.019
This position is very sensitive to the location of Black’s anchor. Moving it forward just one pip is all it takes to make the safer 16/15 13/9 come out on top. Moving the anchor up to the 20pt gives that play an even larger edge. From either of those anchors, Black can already engineer a decent holding game. The “advantage” in having a slotted checker hit is much smaller. Note that 16/11 still fairs poorly in both of these variants.
White - Pips 133
Black - Pips 166
Position 19a. Black to Play 4-1
Code:
XGID=--a---D-D---bD--Aebe-B----:0:0:1:41:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
Pip count X: 166 O: 133 X-O: 0-0
Cube: 1
X to play 41
1. Rollout¹ 16/15 13/9 eq:-0.3232
Player: 41.96% (G:8.16% B:0.28%)
Opponent: 58.04% (G:13.03% B:0.42%)
Confidence: ±0.0067 (-0.3299..-0.3165) - [100.0%]
2. Rollout¹ 13/9 6/5 eq:-0.3832 (-0.0600)
Player: 42.13% (G:8.23% B:0.32%)
Opponent: 57.87% (G:18.47% B:0.64%)
Confidence: ±0.0083 (-0.3915..-0.3749) - [0.0%]
3. Rollout¹ 16/11 eq:-0.4030 (-0.0798)
Player: 39.38% (G:6.99% B:0.23%)
Opponent: 60.62% (G:11.62% B:0.33%)
Confidence: ±0.0064 (-0.4094..-0.3966) - [0.0%]
¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 46439202
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2015-Apr-23
eXtreme Gammon Version: 2.10.199.2658
OpenYourMind.019.AnchorOn21pt.xgp
It is hard to find a variant where 16/11 is correct. The race needs to be much less lopsided. Moving a White checker from his 8pt back to the midpoint won’t do it. Moving two, makes it close. Any further change takes you so far away from the original that you are no longer comparing similar positions.
White - Pips 143
Black - Pips 168
Position 19b. Black to Play 4-1
Code:
XGID=--a---D-D---dD--Acbe--B---:0:0:1:41:0:0:0:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
Pip count X: 168 O: 143 X-O: 0-0
Cube: 1
X to play 41
1. Rollout¹ 16/15 13/9 eq:-0.4330
Player: 39.52% (G:8.34% B:0.29%)
Opponent: 60.48% (G:14.63% B:0.57%)
Confidence: ±0.0031 (-0.4361..-0.4299) - [91.4%]
2. Rollout¹ 13/9 6/5 eq:-0.4363 (-0.0033)
Player: 40.60% (G:8.61% B:0.33%)
Opponent: 59.40% (G:18.27% B:0.83%)
Confidence: ±0.0036 (-0.4399..-0.4327) - [8.6%]
3. Rollout² 16/11 eq:-0.4445 (-0.0115)
Player: 38.38% (G:7.51% B:0.24%)
Opponent: 61.62% (G:11.34% B:0.42%)
Confidence: ±0.0042 (-0.4486..-0.4403) - [0.0%]
¹ 31104 Games rolled with Variance Reduction.
Dice Seed: 46439202
Moves: 3-ply, cube decisions: XG Roller
² 15552 Games rolled with Variance Reduction.
Dice Seed: 46439202
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2015-Apr-23
eXtreme Gammon Version: 2.10.199.2658
OpenYourMind.019.UnstackingWhite's8ptpt.xgp
04-28-2015
, 05:50 AM
Position ID: 78Y5AAC1bQDgQQ Match ID: UokKAAAAAAAE
04-29-2015
, 03:17 AM
White - Pips 58
Black - Pips 144
Black - Pips 144
Code:
1. bar/18 Eq.: -1,125
0,149 0,016 0,000 - 0,851 0,498 0,001 CL -1,184 CF -1,125
2. bar/20 4/2 Eq.: -1,251 ( -0,127)
0,105 0,010 0,000 - 0,895 0,509 0,000 CL -1,289 CF -1,251
White - Pips 58
Black - Pips 149
Black - Pips 149
Code:
1. Rollout bar/18 Eq.: -1,093
0,161 0,017 0,000 - 0,839 0,489 0,001 CL -1,151 CF -1,093
2. bar/20 6/4 Eq.: -1,173 ( -0,081)
0,132 0,013 0,000 - 0,868 0,498 0,000 CL -1,221 CF -1,173
Code:
1. bar/20 4/2 Eq.: -1,279
0,084 0,005 0,000 - 0,916 0,482 0,001 CL -1,310 CF -1,279
2. bar/18 Eq.: -1,295 ( -0,016)
0,097 0,007 0,000 - 0,903 0,532 0,002 CL -1,332 CF -1,295
Moving a black checker from 20 to 7 diminishes the relative value of bar/18:
White - Pips 58
Black - Pips 136
Black - Pips 136
Code:
1. bar/18 Eq.: -0,864
0,167 0,017 0,000 - 0,833 0,259 0,000 CL -0,909 CF -0,864
2. bar/20 6/4 Eq.: -0,907 ( -0,043)
0,136 0,013 0,000 - 0,864 0,229 0,000 CL -0,943 CF -0,907
So as gammon loss is less of an issue in the original position, there is also less to lose with bar/18. The downside comes if white leaves a blot on 17w while black is on the bar. This doesn't outweigh the upsides:
– getting a double shot, with or without two checkers on the 18-point
– if hit, the possibility of entering on the 21-point. This is still more detrimental in case white breaks his 6-point with some 3's (and 1's), or leaves a blot on the 21-point with some unlucky 4.
04-30-2015
, 01:53 AM
White - Pips 64
Black - Pips 132
Position 21. Black to Play 6-5
Jacoby Rule in force and beavers allowed
XGID=-B-BBBB-A--------c--fBBdb-:1:1:1:65:0:0:3:0:10
This is one I botched over the board.
Mike
Black - Pips 132
Position 21. Black to Play 6-5
Jacoby Rule in force and beavers allowed
XGID=-B-BBBB-A--------c--fBBdb-:1:1:1:65:0:0:3:0:10
This is one I botched over the board.
Mike
05-02-2015
, 02:13 AM
White - Pips 64
Black - Pips 132
Position 21. Black to Play 6-5
Jacoby Rule in force and beavers allowed
XGID=-B-BBBB-A--------c--fBBdb-:1:1:1:65:0:0:3:0:10
In these sorts of positions, breaking the front anchor is almost automatic, so I gave myself a pat on the back for being open to the alternative. I thought I was very clever to observe that I could create several blotting 5s for my opponent by breaking from the rear. After moving 22/11, the rolls 53, 54, and 56 all become blotting numbers, with the last of them forcing two blots. Unfortunately, 22/11 is the wrong play. It is, in fact, a whopper.
One problem is that the direct shots that result are all single shots. If I break the front anchor instead, I increase the odds of getting a double shot at any blot that might appear. More significantly, when I keep the rear anchor, my opponent will have a tougher time clearing both the 17pt and the 20pt.
Breaking the rear anchor generates more shots on the next roll. In the long run, however, it eases the opponent’s burden of clearing.
My 5k rollout follows.
Mike
5k XG2 Rollout – Jacoby Rule in force and beavers allowed
Black - Pips 132
Position 21. Black to Play 6-5
Jacoby Rule in force and beavers allowed
XGID=-B-BBBB-A--------c--fBBdb-:1:1:1:65:0:0:3:0:10
In these sorts of positions, breaking the front anchor is almost automatic, so I gave myself a pat on the back for being open to the alternative. I thought I was very clever to observe that I could create several blotting 5s for my opponent by breaking from the rear. After moving 22/11, the rolls 53, 54, and 56 all become blotting numbers, with the last of them forcing two blots. Unfortunately, 22/11 is the wrong play. It is, in fact, a whopper.
One problem is that the direct shots that result are all single shots. If I break the front anchor instead, I increase the odds of getting a double shot at any blot that might appear. More significantly, when I keep the rear anchor, my opponent will have a tougher time clearing both the 17pt and the 20pt.
Breaking the rear anchor generates more shots on the next roll. In the long run, however, it eases the opponent’s burden of clearing.
My 5k rollout follows.
Mike
5k XG2 Rollout – Jacoby Rule in force and beavers allowed
Code:
XGID=-B-BBBB-A--------c--fBBdb-:1:1:1:65:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
Pip count X: 132 O: 64 X-O: 0-0
Cube: 2, X own cube
X to play 65
1. Rollout¹ 21/10 eq:-0.2987
Player: 34.86% (G:3.43% B:0.08%)
Opponent: 65.14% (G:14.51% B:0.10%)
Confidence: ±0.0026 (-0.3013..-0.2961) - [100.0%]
Duration: 7 minutes 15 seconds
2. Rollout¹ 21/15 8/3 eq:-0.3159 (-0.0172)
Player: 34.20% (G:3.16% B:0.07%)
Opponent: 65.80% (G:15.91% B:0.10%)
Confidence: ±0.0025 (-0.3184..-0.3134) - [0.0%]
Duration: 6 minutes 40 seconds
3. Rollout¹ 21/16 8/2 eq:-0.3372 (-0.0385)
Player: 34.38% (G:3.31% B:0.08%)
Opponent: 65.62% (G:17.92% B:0.14%)
Confidence: ±0.0028 (-0.3400..-0.3344) - [0.0%]
Duration: 6 minutes 22 seconds
4. Rollout¹ 21/16 21/15 eq:-0.3465 (-0.0479)
Player: 31.05% (G:2.34% B:0.06%)
Opponent: 68.95% (G:9.15% B:0.05%)
Confidence: ±0.0028 (-0.3493..-0.3437) - [0.0%]
Duration: 8 minutes 04 seconds
5. Rollout¹ 22/11 eq:-0.4222 (-0.1236)
Player: 30.97% (G:3.48% B:0.10%)
Opponent: 69.03% (G:18.20% B:0.06%)
Confidence: ±0.0024 (-0.4247..-0.4198) - [0.0%]
Duration: 8 minutes 45 seconds
¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 31715667
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2015-Apr-19
eXtreme Gammon Version: 2.10.199.2658
05-02-2015
, 02:24 AM
White - Pips 60
Black - Pips 132
Problem 21 Variant – Black to Play 6-5
Here is a variant where breaking from the rear is correct.
XGR++ Eval
Black - Pips 132
Problem 21 Variant – Black to Play 6-5
Here is a variant where breaking from the rear is correct.
XGR++ Eval
Code:
XGID=-B-BBBB-A--------c--fBB-f-:1:1:1:65:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
Pip count X: 132 O: 60 X-O: 0-0
Cube: 2, X own cube
X to play 65
1. XG Roller++ 22/11 eq:-0.0344
Player: 43.61% (G:9.34% B:0.35%)
Opponent: 56.39% (G:13.54% B:0.04%)
2. XG Roller++ 21/10 eq:-0.0917 (-0.0574)
Player: 42.63% (G:6.32% B:0.18%)
Opponent: 57.37% (G:12.32% B:0.05%)
eXtreme Gammon Version: 2.10
05-03-2015
, 03:46 AM
Position ID: mM9GESCwuwdgQA Match ID: cIkKAAAAAAAE
05-04-2015
, 07:24 AM
White - Pips 137
Black - Pips 142
Black - Pips 142
Code:
1. bar/18 Eq.: +0,614
0,652 0,159 0,005 - 0,348 0,060 0,002 CL +0,407 CF +0,614
2. bar/23 18/13* Eq.: +0,502 ( -0,112)
0,621 0,226 0,020 - 0,379 0,125 0,008 CL +0,357 CF +0,502
White - Pips 137
Black - Pips 130
Black - Pips 130
Code:
1. bar/18 Eq.: +0,945
0,713 0,238 0,005 - 0,287 0,048 0,001 CL +0,620 CF +0,945
2. bar/23 18/13* Eq.: +0,904 ( -0,040)
0,694 0,360 0,043 - 0,306 0,083 0,005 CL +0,705 CF +0,904
White - Pips 155
Black - Pips 142
Black - Pips 142
Code:
1. bar/18 Eq.: +0,957
0,722 0,210 0,010 - 0,278 0,055 0,001 CL +0,608 CF +0,957
2. bar/23 18/13* Eq.: +0,675 ( -0,282)
0,643 0,260 0,030 - 0,357 0,097 0,005 CL +0,474 CF +0,675
Moving 12w to 17:
White - Pips 132
Black - Pips 142
Black - Pips 142
Code:
1. bar/23 18/13* Eq.: +0,506
0,627 0,200 0,014 - 0,373 0,120 0,007 CL +0,340 CF +0,506
2. bar/18 Eq.: +0,470 ( -0,035)
0,622 0,124 0,004 - 0,378 0,063 0,002 CL +0,306 CF +0,470
Moving 8b to 5:
White - Pips 137
Black - Pips 139
Black - Pips 139
Code:
1. bar/18 Eq.: +0,829
0,694 0,183 0,006 - 0,306 0,052 0,002 CL +0,524 CF +0,829
2. bar/23 18/13* Eq.: +0,599 ( -0,230)
0,635 0,254 0,025 - 0,365 0,117 0,007 CL +0,424 CF +0,599
Conclusion:
Safe play is superior because it gives black a better opportunity to lengthen his prime, he has a small piplead, and his homeboard is not much better.
However, if you are the better player the hitting play might be better because it will lead to many more difficult positions.
05-05-2015
, 11:20 AM
Position ID: uL2DAEGbmR0IEA Match ID: QwkGAAAAAAAE
05-05-2015
, 11:44 AM