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interests / rec.games.backgammon / Re: 5pt problem 2

SubjectAuthor
* 5pt problem 2Timothy Chow
+* Re: 5pt problem 2ah...Clem
|`- Re: 5pt problem 2Timothy Chow
`- Rollout: 5pt problem 2Timothy Chow

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5pt problem 2

<tjdu3n$2ood7$3@dont-email.me>

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From: tchow12...@yahoo.com (Timothy Chow)
Newsgroups: rec.games.backgammon
Subject: 5pt problem 2
Date: Thu, 27 Oct 2022 08:38:15 -0400
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 by: Timothy Chow - Thu, 27 Oct 2022 12:38 UTC

XGID=--aBa-DBB---bD-b---eb-b-A-:0:0:1:31:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O X |
| X O | | O O O |
| X | | O |
| X | | O |
| | | O |
| |BAR| |
| | | |
| | | X |
| | | X |
| O X X | | X X |
| O X X | | X O X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 136 O: 136 X-O: 0-0
Cube: 1
X to play 31

---
Tim Chow

Re: 5pt problem 2

<tje7eq$2nhus$3@dont-email.me>

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From: ah_c...@ymail.com (ah...Clem)
Newsgroups: rec.games.backgammon
Subject: Re: 5pt problem 2
Date: Thu, 27 Oct 2022 11:17:15 -0400
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In-Reply-To: <tjdu3n$2ood7$3@dont-email.me>
 by: ah...Clem - Thu, 27 Oct 2022 15:17 UTC

On 10/27/2022 8:38 AM, Timothy Chow wrote:
> XGID=--aBa-DBB---bD-b---eb-b-A-:0:0:1:31:0:0:0:0:10
>
> Score is X:0 O:0. Unlimited Game
>  +13-14-15-16-17-18------19-20-21-22-23-24-+
>  | X     O          |   | O  O     O     X |
>  | X     O          |   | O  O     O       |
>  | X                |   | O                |
>  | X                |   | O                |
>  |                  |   | O                |
>  |                  |BAR|                  |
>  |                  |   |                  |
>  |                  |   | X                |
>  |                  |   | X                |
>  | O           X  X |   | X        X       |
>  | O           X  X |   | X     O  X  O    |
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count  X: 136  O: 136 X-O: 0-0
> Cube: 1
> X to play 31

Making the five point exposes a double shot while O has a strong board.
Magriel's safe v bold criteria all point to a safe play.

I'll try 24/23 to see more daylight and then 6/3 to unstack and minimize
shots.

Rollout: 5pt problem 2

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From: tchow12...@yahoo.com (Timothy Chow)
Newsgroups: rec.games.backgammon
Subject: Rollout: 5pt problem 2
Date: Sat, 29 Oct 2022 08:09:26 -0400
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 by: Timothy Chow - Sat, 29 Oct 2022 12:09 UTC

XGID=--aBa-DBB---bD-b---eb-b-A-:0:0:1:31:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O X |
| X O | | O O O |
| X | | O |
| X | | O |
| | | O |
| |BAR| |
| | | |
| | | X |
| | | X |
| O X X | | X X |
| O X X | | X O X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 136 O: 136 X-O: 0-0
Cube: 1
X to play 31

Making the 5pt is often worth it even if it leaves a double direct shot,
but in this position, XG balks. The 8pt is also valuable in this
position, and X has a much safer play (24/23 6/3) whose only real
disadvantage is that it creates a dilly builder.

1. Rollout¹ 24/23 6/3 eq:-0.210
Player: 46.37% (G:10.34% B:0.44%)
Opponent: 53.63% (G:19.42% B:0.45%)
Confidence: ±0.013 (-0.223..-0.197) - [100.0%]

2. Rollout¹ 8/5 6/5 eq:-0.285 (-0.075)
Player: 44.68% (G:13.12% B:0.62%)
Opponent: 55.32% (G:22.76% B:0.79%)
Confidence: ±0.012 (-0.296..-0.273) - [0.0%]

3. Rollout¹ 6/2* eq:-0.291 (-0.081)
Player: 44.40% (G:12.04% B:0.49%)
Opponent: 55.60% (G:21.83% B:0.70%)
Confidence: ±0.014 (-0.304..-0.277) - [0.0%]

4. Rollout¹ 7/4* 4/3 eq:-0.305 (-0.095)
Player: 43.50% (G:13.03% B:0.51%)
Opponent: 56.50% (G:22.03% B:0.77%)
Confidence: ±0.012 (-0.317..-0.293) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.211.pre-release

---
Tim Chow

Re: 5pt problem 2

<tjj59c$3f986$3@dont-email.me>

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From: tchow12...@yahoo.com (Timothy Chow)
Newsgroups: rec.games.backgammon
Subject: Re: 5pt problem 2
Date: Sat, 29 Oct 2022 08:11:24 -0400
Organization: A noiseless patient Spider
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 by: Timothy Chow - Sat, 29 Oct 2022 12:11 UTC

On 10/27/2022 11:17 AM, ah...Clem wrote:
> On 10/27/2022 8:38 AM, Timothy Chow wrote:
>> XGID=--aBa-DBB---bD-b---eb-b-A-:0:0:1:31:0:0:0:0:10
>>
>> Score is X:0 O:0. Unlimited Game
>>  +13-14-15-16-17-18------19-20-21-22-23-24-+
>>  | X     O          |   | O  O     O     X |
>>  | X     O          |   | O  O     O       |
>>  | X                |   | O                |
>>  | X                |   | O                |
>>  |                  |   | O                |
>>  |                  |BAR|                  |
>>  |                  |   |                  |
>>  |                  |   | X                |
>>  |                  |   | X                |
>>  | O           X  X |   | X        X       |
>>  | O           X  X |   | X     O  X  O    |
>>  +12-11-10--9--8--7-------6--5--4--3--2--1-+
>> Pip count  X: 136  O: 136 X-O: 0-0
>> Cube: 1
>> X to play 31
>
>
> Making the five point exposes a double shot while O has a strong board.
> Magriel's safe v bold criteria all point to a safe play.

I would say that most of Magriel's criteria either don't apply or are
inconclusive here---neither player has an anchor, and after X makes the
5pt, the boards are equally strong. The one clear criterion is that
O has more checkers back.

---
Tim Chow

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