I've seen a position very similar to the below misplayed at quite
a high level. (I can't remember the name of the misplayer but I think
he was somewhat well-known).
When the main issue is whether or not you lose a gammon, and
all the stay-back plays lose significant numbers of pips, staying back
may still be correct anyway as a means of slowing down your opponent's
bearoff. Leaving frees your opponent to leave blots.
Staying back is correct in the position below.
Admittedly, I haven't rolled it out, but I don't feel I need to.
But the title of my post is "Good news and bad news."
The title doesn't seem to fit the content of the post, does it?
Ok, just be a bit patient -- the title justification comes now.
The bad news: I did misplay the position by leaving.
The good news: All my other plays were optimal or near-optimal,
so I finished the game with a PR of approximately 2.0.

Paul

XGID=--AB-BDAC-A----------bAfc-:1:1:1:64:0:0:3:0:10
X:Daniel O:eXtremeGammon

Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O X O O |
| | | O O O |
| | | O O |
| | | O |
| | | 6 |
| |BAR| |
| | | |
| | | X |
| X | | X | +---+
| X | | X X X | | 2 |
| X X X | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 105 O: 23 X-O: 0-0
Cube: 2, X own cube
X to play 64

1. XG Roller+ 10/4 8/4 eq:-1.040
Player: 4.99% (G:0.00% B:0.00%)
Opponent: 95.01% (G:15.87% B:0.03%)

2. XG Roller+ 22/16 10/6 eq:-1.097 (-0.057)
Player: 0.00% (G:0.00% B:0.00%)
Opponent: 100.00% (G:9.71% B:0.00%)

3. 4-ply 10/6 8/2 eq:-1.080 (-0.039)
Player: 3.84% (G:0.00% B:0.00%)
Opponent: 96.16% (G:16.98% B:0.02%)

4. 4-ply 8/4 8/2 eq:-1.081 (-0.041)
Player: 4.93% (G:0.00% B:0.00%)
Opponent: 95.07% (G:19.82% B:0.03%)

5. 3-ply 22/12 eq:-1.102 (-0.062)
Player: 0.02% (G:0.00% B:0.00%)
Opponent: 99.98% (G:10.27% B:0.00%)


eXtreme Gammon Version: 2.10

--- SoupGate-Win32 v1.05
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On 12/20/2021 8:46 AM, I wrote:

But the rollout below shows that XG runs at gammon save.

More precisely, I should have said that the rollout below
shows that XG *favors running* at gammon save. XG does
in fact run at gammon save, but the rollout doesn't show
that (in principle the top play of a gammon save rollout
could differ from the move that XG plays at gammon save).

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 12/20/2021 4:46 AM, peps...@gmail.com wrote:

When the main issue is whether or not you lose a gammon, and
all the stay-back plays lose significant numbers of pips, staying back
may still be correct anyway as a means of slowing down your opponent's bearoff. Leaving frees your opponent to leave blots.

It's an interesting position but I wouldn't analyze it this way.
When you say that the main issue is whether or not you lose a
gammon, it makes it sound like you would make the same play at
gammon save. But the rollout below shows that XG runs at gammon save.

Staying back and making a strong point in your board comes out ahead
in your position because it gives you enough winning chances (by
getting and hitting a shot) to compensate for the extra gammons lost.


XGID=--AB-BDAC-A----------bAfc-:0:0:1:64:1:0:1:2:10

X:Player 1 O:Player 2
Score is X:1 O:0 2 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O X O O |
| | | O O O |
| | | O O |
| | | O |
| | | 6 |
| |BAR| |
| | | |
| | | X |
| X | | X |
| X | | X X X |
| X X X | | X X X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 105 O: 23 X-O: 1-0/2 Crawford
Cube: 1
X to play 64

1. Rollout¹ 22/16 10/6 eq:-1.190
Player: 0.00% (G:0.00% B:0.00%)
Opponent: 100.00% (G:9.52% B:0.00%)
Confidence: ±0.001 (-1.191..-1.190) - [100.0%]

2. Rollout¹ 22/12 eq:-1.200 (-0.010)
Player: 0.00% (G:0.00% B:0.00%)
Opponent: 100.00% (G:10.00% B:0.00%)
Confidence: ±0.001 (-1.201..-1.199) - [0.0%]

3. Rollout¹ 10/4 8/4 eq:-1.214 (-0.023)
Player: 4.94% (G:0.00% B:0.00%)
Opponent: 95.06% (G:15.62% B:0.06%)
Confidence: ±0.001 (-1.215..-1.212) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves and cube decisions: XG Roller+
Search interval: Huge

eXtreme Gammon Version: 2.19.207.pre-release, MET: Kazaross XG2

---
Tim Chow

--- SoupGate-Win32 v1.05
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On Monday, December 20, 2021 at 1:49:24 PM UTC, Tim Chow wrote:

On 12/20/2021 8:46 AM, I wrote:

But the rollout below shows that XG runs at gammon save.

More precisely, I should have said that the rollout below
shows that XG *favors running* at gammon save. XG does
in fact run at gammon save, but the rollout doesn't show
that (in principle the top play of a gammon save rollout
could differ from the move that XG plays at gammon save).

Yes, my analysis was messed up. It's hard to get these positions right and there's
a fair amount of equity at stake.

Thanks for your comments.

Paul

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