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interests / rec.games.backgammon / Rollout: Double from the bar?

XGID=-bBBBBC-----AB---a-db-bbbA:0:0:1:00:0:0:0:5:10

X:X O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O O O |
| X | | O O O O O |
| | | O |
| | | O |
| | X | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 109 O: 102 X-O: 0-0/5
Cube: 1
X on roll, cube action

Re: Double from the bar?

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Subject: Re: Double from the bar?
From: pepste...@gmail.com (peps...@gmail.com)
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by: peps...@gmail.com - Thu, 29 Sep 2022 20:43 UTC

On Thursday, September 29, 2022 at 4:28:21 PM UTC+1, ah...Clem wrote:
> XGID=-bBBBBC-----AB---a-db-bbbA:0:0:1:00:0:0:0:5:10
>
> X:X O:O
> Score is X:0 O:0 5 pt.(s) match.
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X O | | O O O O O |
> | X | | O O O O O |
> | | | O |
> | | | O |
> | | X | |
> | |BAR| |
> | | | |
> | | | |
> | | | X |
> | | | X X X X X O |
> | X | | X X X X X O |
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 109 O: 102 X-O: 0-0/5
> Cube: 1
> X on roll, cube action

Easy take, not sure about the double.
The sequences where we dance and the opponent springs a 6 are very good for the opponent, who
would then be targeting a blot.
I think that if the opponent doesn't roll a 6, we can lose our market even if we dance.

D/T. I'm not sure. And I think it's a great problem.
My second choice might be ND/T but D/P wouldn't amaze me.
TG/P and TG/T (possible in a match) are the only ones I would rule out.
Because D/P wouldn't amaze me, and I'm a fairly good player by normal standards,
your mantra "double because they might pass even though it's ND/T" might make sense
_in this particular position_ but I wouldn't apply it so universally as you do.

When I say D/T, I'm saying it because that's my verdict about optimal theoretical play.
I don't know though.

Paul

Re: Double from the bar?

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From: tchow12...@yahoo.com (Timothy Chow)
Newsgroups: rec.games.backgammon
Subject: Re: Double from the bar?
Date: Thu, 29 Sep 2022 21:13:19 -0400
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by: Timothy Chow - Fri, 30 Sep 2022 01:13 UTC

On 9/29/2022 11:28 AM, ah...Clem wrote:
> XGID=-bBBBBC-----AB---a-db-bbbA:0:0:1:00:0:0:0:5:10
>
> X:X O:O
> Score is X:0 O:0 5 pt.(s) match.
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X O | | O O O O O |
> | X | | O O O O O |
> | | | O |
> | | | O |
> | | X | |
> | |BAR| |
> | | | |
> | | | |
> | | | X |
> | | | X X X X X O |
> | X | | X X X X X O |
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 109 O: 102 X-O: 0-0/5
> Cube: 1
> X on roll, cube action
>

I'm not sure O can take this. Certainly if X dances and O rolls
an immediate 6 then X is in trouble. But if O doesn't roll a 6
soon then her position is going to deteriorate rapidly. Though
both players have five-point boards, X's board is a much bigger
threat; if, in the ensuing play, X gets hit, it's bad but maybe
not fatal because of O's open 4pt, but if O gets hit then she's
in really big trouble. I'm going to go with D/P.

---
Tim Chow

Rollout: Double from the bar?

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From: ah_c...@ymail.com (ah...Clem)
Newsgroups: rec.games.backgammon
Subject: Rollout: Double from the bar?
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by: ah...Clem - Fri, 30 Sep 2022 18:47 UTC

This one is all about timing. X is stuck on the bar, O is stuck behind a
solid five prime. X needs a four, O needs a six, and since neither are
probable, this situation can go on for several rolls, which it did otb.

As long as both players are stuck, X's position remains static, while
O's position deteriorates with each sequence. So, the question is how
far to let it deteriorate before shipping the cube?

This position is when the cube became ripe. X still has about 35% GWC
but X has enough market losers to ship it.

The variants below are the previous cube decision (which was ND) and the
next two. You can see it go from ND to D/T to D/P. I waited until it
was D/P and missed three cubes, although this first one was not too costly.

Note that if O leaps and X dances (twice) it's a cash for O.

XGID=-bBBBBC-----AB---a-db-bbbA:0:0:1:00:0:0:0:5:10

X:You O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O O O |
| X | | O O O O O |
| | | O |
| | | O |
| | X | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 109 O: 102 X-O: 0-0/5
Cube: 1
X on roll, cube action

Analyzed in Rollout
No double
Player Winning Chances: 65.51% (G:18.01% B:0.86%)
Opponent Winning Chances: 34.49% (G:15.15% B:0.18%)
Double/Take
Player Winning Chances: 65.77% (G:17.98% B:0.94%)
Opponent Winning Chances: 34.23% (G:14.94% B:0.22%)

Cubeless Equities: No Double=+0.345, Double=+0.695

Cubeful Equities:
No double: +0.490 (-0.059)
Double/Take: +0.549
Double/Pass: +1.000 (+0.451)

Best Cube action: Double / Take

Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: ± 0.008 (+0.482..+0.498)
Confidence Double: ± 0.013 (+0.536..+0.562)

Double Decision confidence: 100.0%
Take Decision confidence: 100.0%

Duration: 3 minutes 04 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

*////////////////////////////
* variant1, previous cube decision
*/////////////////////////////

Not a cube yet, but might be a good practical one since some will pass

XGID=-bBBBBC-----AB--ab-bb-bbbA:0:0:1:00:0:0:0:5:10

X:You O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O O | | O O O O O |
| X O | | O O O O O |
| | | |
| | | |
| | X | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 109 O: 107 X-O: 0-0/5
Cube: 1
X on roll, cube action

Analyzed in XG Roller++
Player Winning Chances: 61.02% (G:18.13% B:1.20%)
Opponent Winning Chances: 38.98% (G:18.55% B:0.22%)

Cubeless Equities: No Double=+0.229, Double=+0.427

Cubeful Equities:
No double: +0.318
Double/Take: +0.275 (-0.044)
Double/Pass: +1.000 (+0.682)

Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 5.7%

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

*///////////////////////////
* variant 2 - next roll
*///////////////////////////
Missing the cube here is a double whopper, but still a take

XGID=-bBBBBC-----AB---a-cb-bcbA:0:0:1:00:0:0:0:5:10

X:You O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O O O |
| X | | O O O O O |
| | | O O |
| | | |
| | X | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 109 O: 98 X-O: 0-0/5
Cube: 1
X on roll, cube action

Analyzed in XG Roller++
Player Winning Chances: 70.15% (G:18.51% B:0.71%)
Opponent Winning Chances: 29.85% (G:11.30% B:0.09%)

Cubeless Equities: No Double=+0.476, Double=+0.977

Cubeful Equities:
No double: +0.613 (-0.222)
Double/Take: +0.835
Double/Pass: +1.000 (+0.165)

Best Cube action: Double / Take

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

*/////////////////////////////////
* variant 3 and the following roll
*////////////////////////////////

We're in double/pass territory now

XGID=-bBBBBC-----AB-----cb-bdbA:0:0:1:00:0:0:0:5:10

X:You O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X | | O O O O O |
| X | | O O O O O |
| | | O O |
| | | O |
| | X | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 109 O: 92 X-O: 0-0/5
Cube: 1
X on roll, cube action

Analyzed in XG Roller++
Player Winning Chances: 76.57% (G:21.60% B:0.85%)
Opponent Winning Chances: 23.43% (G:7.18% B:0.05%)

Cubeless Equities: No Double=+0.673, Double=+1.409

Cubeful Equities:
No double: +0.775 (-0.225)
Double/Take: +1.290 (+0.290)
Double/Pass: +1.000

Best Cube action: Double / Pass

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Subject	Author
Double from the bar?	ah...Clem
Re: Double from the bar?	peps...@gmail.com
Re: Double from the bar?	Timothy Chow
Rollout: Double from the bar?	ah...Clem