Whether or not to break anchor is a decision that I continue
to find difficult. Here's the first of a series of positions
in which breaking anchor is one of the options.

XGID=-ABbCCB-----bB-----bdbcB--:1:1:1:52:0:0:0:0:10

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 O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | X X | +---+
| O | | X X X O X | | 2 |
| O | | X X X O X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 116 O: 119 X-O: 0-0
Cube: 2, X own cube
X to play 52

---
Tim Chow

On 12/5/2022 9:19 AM, Timothy Chow wrote:
> Whether or not to break anchor is a decision that I continue
> to find difficult.  Here's the first of a series of positions
> in which breaking anchor is one of the options.
>
> XGID=-ABbCCB-----bB-----bdbcB--:1:1:1:52:0:0:0:0:10
>
> 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     O       |
>  |                  |   |    O             |
>  |                  |   |                  |
>  |                  |BAR|                  |
>  |                  |   |                  |
>  |                  |   |                  |
>  |                  |   |    X  X          | +---+
>  | O                |   | X  X  X  O  X    | | 2 |
>  | O                |   | X  X  X  O  X  X | +---+
>  +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count  X: 116  O: 119 X-O: 0-0
> Cube: 2, X own cube
> X to play 52

O will hit loose if we break anchor, and that's any 1, 4, or 3. Seems
like too many shots, and with 11 in the zone (maybe 12 or 13 after the
hit X gets blown off the board too often for my liking.

13/6 leaves 14 shots, but at least we have the deep anchor if we're hit.
OTOH, keeping the midpoint has a lot of advantages.

Clearing the six point looks ugly, but seems to be the least bad option,
so I'll play that. 6/1 6/4.

--
Ah....Clem
The future is fun, the future is fair.

On Monday, December 5, 2022 at 9:19:58 AM UTC-5, Tim Chow wrote:
> Whether or not to break anchor is a decision that I continue
> to find difficult. Here's the first of a series of positions
> in which breaking anchor is one of the options.
>
> XGID=-ABbCCB-----bB-----bdbcB--:1:1:1:52:0:0:0:0:10
>
> 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 O |
> | | | O |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | | | X X | +---+
> | O | | X X X O X | | 2 |
> | O | | X X X O X X | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 116 O: 119 X-O: 0-0
> Cube: 2, X own cube
> X to play 52
>
> ---
> Tim Chow

Obv we run with any number that duplicates. ([62] for eg) Obv we run with any number that hops and covers [64 63 54 53] and yes, we just run all the way w/64. If it doesn't duplicate or doesn't jump and cover we stay where we are.

Stick

On 12/5/2022 7:39 PM, Stick Rice wrote:

> Obv we run with any number that duplicates. ([62] for eg) Obv we run with any number that hops and covers [64 63 54 53] and yes, we just run all the way w/64. If it doesn't duplicate or doesn't jump and cover we stay where we are.

Good analysis. It nicely reduces the choice to either running off the
midpoint or clearing the six, which were my two candidate plays.

It may be obvious to you that one of these plays is better than the
other, but it isn't to me.

XGID=-ABbCCB-----bB-----bdbcB--:1:1:1:52:0:0:0:0:10

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 O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | X X | +---+
| O | | X X X O X | | 2 |
| O | | X X X O X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 116 O: 119 X-O: 0-0
Cube: 2, X own cube
X to play 52

As is often the case, an excellent starting point is Woolsey's
article on the subject.

https://www.bkgm.com/articles/GOL/Sep02/anchor.htm

Breaking anchor is a kind of pay now/pay later decision, in the
sense that breaking anchor typically exposes you to attack right
away, while waiting risks being forced to break anchor later under
less favorable circumstances. Here, timing considerations slightly
lean toward breaking anchor now, while board strength considerations
point toward breaking anchor later. The balance is delicate and
requires carefully assessing O's attacking potential.

It's too soon to rip up our board, so 13/6 is the main alternative.
For the variant, I have covered X's 1pt blot with the spare from
the 4pt. This strengthens X's board and also slightly worsens his
flexibility and timing. In the variant, XG runs.

1. Rollout¹ 13/6 eq:-0.233
Player: 35.96% (G:9.56% B:0.35%)
Opponent: 64.04% (G:16.31% B:0.81%)
Confidence: ±0.007 (-0.240..-0.225) - [100.0%]

2. Rollout¹ 23/16 eq:-0.362 (-0.130)
Player: 35.81% (G:14.25% B:0.60%)
Opponent: 64.19% (G:32.49% B:1.13%)
Confidence: ±0.008 (-0.370..-0.355) - [0.0%]

3. Rollout¹ 6/4 6/1 eq:-0.382 (-0.149)
Player: 32.79% (G:6.92% B:0.12%)
Opponent: 67.21% (G:22.14% B:0.93%)
Confidence: ±0.008 (-0.390..-0.374) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.211.pre-release

-------
Variant
-------

XGID=-BBbBCB-----bB-----bdbcB--:1:1:1:52:0:0:0:0:10

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 O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | X | +---+
| O | | X X X O X X | | 2 |
| O | | X X X O X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 113 O: 119 X-O: 0-0
Cube: 2, X own cube
X to play 52

1. Rollout¹ 23/16 eq:-0.148
Player: 41.27% (G:15.58% B:0.56%)
Opponent: 58.73% (G:25.31% B:0.64%)
Confidence: ±0.008 (-0.156..-0.140) - [100.0%]

2. Rollout¹ 13/6 eq:-0.186 (-0.038)
Player: 37.69% (G:9.39% B:0.22%)
Opponent: 62.31% (G:15.07% B:0.63%)
Confidence: ±0.006 (-0.192..-0.180) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.211.pre-release

---
Tim Chow