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A cube error

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Subject: A cube error
From: pepste...@gmail.com (peps...@gmail.com)
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by: peps...@gmail.com - Fri, 22 Dec 2023 13:16 UTC

I would be grateful to anyone who could explain why my redouble to 4
is so weak. The high no-double equity of 0.6 indicates that I have a strong
position and XG is hugely vulnerable to gammons. I see the position has
volatile with my 3s being powerful.
I suppose one factor is that XG can partially kill my gammons by redoubling
to 8 which is exactly what XG did later in the game.
Cubing still looks fine to me. I'm sure it's a money double.
Explanations would be very welcome. Or has the
kill-my-gammons-by-redoubling point answered my own question.

Paul

XGID=abB-B-C-B-a-bDa--A-bbbbA--:1:1:1:00:2:0:0:11:10

X:Daniel O:XG Roller+
Score is X:2 O:0 11 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O X | | O O O O X |
| X | | O O O O |
| X | | |
| X | | |
| | | |
| |BAR| |
| | O | |
| | | |
| | | X | +---+
| O X | | X X X O | | 2 |
| O O X | | X X X O | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 138 O: 161 X-O: 2-0/11
Cube: 2, X own cube
X on roll, cube action

Analyzed in XG Roller+
Player Winning Chances: 62.15% (G:30.88% B:4.85%)
Opponent Winning Chances: 37.85% (G:9.27% B:0.46%)

Cubeless Equities: No Double=+0.498, Double=+0.772

Cubeful Equities:
No redouble: +0.607
Redouble/Take: +0.328 (-0.280)
Redouble/Pass: +1.000 (+0.393)

Best Cube action: No redouble / Take
Percentage of wrong pass needed to make the double decision right: 29.4%

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Re: A cube error

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From: tchow12...@yahoo.com (Timothy Chow)
Newsgroups: rec.games.backgammon
Subject: Re: A cube error
Date: Fri, 22 Dec 2023 10:10:33 -0500
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by: Timothy Chow - Fri, 22 Dec 2023 15:10 UTC

I think you have mostly answered your own question. For starters,
XG says it's barely a money redouble. In general, when you are
ahead in the match score, you should be cautious about redoubling
in gammonish positions. Not only do you risk devaluing your own
gammons, you amplify the effect of your opponent's gammons.

You don't have to be much ahead in the match score for this effect
to be substantial. Suppose you were leading 2-0 in a 17-point match.
XG would still hate your redouble to 4. If your opponent re-redoubles
to 8 and then wins a gammon, then they've practically won the match.
They don't need to win that many gammons for this possibility to
loom large.

---
Tim Chow

On 12/22/2023 8:16 AM, peps...@gmail.com wrote:
> I would be grateful to anyone who could explain why my redouble to 4
> is so weak. The high no-double equity of 0.6 indicates that I have a strong
> position and XG is hugely vulnerable to gammons. I see the position has
> volatile with my 3s being powerful.
> I suppose one factor is that XG can partially kill my gammons by redoubling
> to 8 which is exactly what XG did later in the game.
> Cubing still looks fine to me. I'm sure it's a money double.
> Explanations would be very welcome. Or has the
> kill-my-gammons-by-redoubling point answered my own question.
>
> Paul
>
> XGID=abB-B-C-B-a-bDa--A-bbbbA--:1:1:1:00:2:0:0:11:10
>
> X:Daniel O:XG Roller+
> Score is X:2 O:0 11 pt.(s) match.
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X O X | | O O O O X |
> | X | | O O O O |
> | X | | |
> | X | | |
> | | | |
> | |BAR| |
> | | O | |
> | | | |
> | | | X | +---+
> | O X | | X X X O | | 2 |
> | O O X | | X X X O | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 138 O: 161 X-O: 2-0/11
> Cube: 2, X own cube
> X on roll, cube action
>
> Analyzed in XG Roller+
> Player Winning Chances: 62.15% (G:30.88% B:4.85%)
> Opponent Winning Chances: 37.85% (G:9.27% B:0.46%)
>
> Cubeless Equities: No Double=+0.498, Double=+0.772
>
> Cubeful Equities:
> No redouble: +0.607
> Redouble/Take: +0.328 (-0.280)
> Redouble/Pass: +1.000 (+0.393)
>
> Best Cube action: No redouble / Take
> Percentage of wrong pass needed to make the double decision right: 29.4%
>
> eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Re: A cube error

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Subject: Re: A cube error
From: bananabo...@gmail.com (Stick Rice)
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by: Stick Rice - Mon, 1 Jan 2024 19:09 UTC

On Friday, December 22, 2023 at 10:10:36 AM UTC-5, Timothy Chow wrote:
> I think you have mostly answered your own question. For starters,
> XG says it's barely a money redouble. In general, when you are
> ahead in the match score, you should be cautious about redoubling
> in gammonish positions. Not only do you risk devaluing your own
> gammons, you amplify the effect of your opponent's gammons.
>
> You don't have to be much ahead in the match score for this effect
> to be substantial. Suppose you were leading 2-0 in a 17-point match.
> XG would still hate your redouble to 4. If your opponent re-redoubles
> to 8 and then wins a gammon, then they've practically won the match.
> They don't need to win that many gammons for this possibility to
> loom large.
>
> ---
> Tim Chow
> On 12/22/2023 8:16 AM, peps...@gmail.com wrote:
> > I would be grateful to anyone who could explain why my redouble to 4
> > is so weak. The high no-double equity of 0.6 indicates that I have a strong
> > position and XG is hugely vulnerable to gammons. I see the position has
> > volatile with my 3s being powerful.
> > I suppose one factor is that XG can partially kill my gammons by redoubling
> > to 8 which is exactly what XG did later in the game.
> > Cubing still looks fine to me. I'm sure it's a money double.
> > Explanations would be very welcome. Or has the
> > kill-my-gammons-by-redoubling point answered my own question.
> >
> > Paul
> >
> > XGID=abB-B-C-B-a-bDa--A-bbbbA--:1:1:1:00:2:0:0:11:10
> >
> > X:Daniel O:XG Roller+
> > Score is X:2 O:0 11 pt.(s) match.
> > +13-14-15-16-17-18------19-20-21-22-23-24-+
> > | X O X | | O O O O X |
> > | X | | O O O O |
> > | X | | |
> > | X | | |
> > | | | |
> > | |BAR| |
> > | | O | |
> > | | | |
> > | | | X | +---+
> > | O X | | X X X O | | 2 |
> > | O O X | | X X X O | +---+
> > +12-11-10--9--8--7-------6--5--4--3--2--1-+
> > Pip count X: 138 O: 161 X-O: 2-0/11
> > Cube: 2, X own cube
> > X on roll, cube action
> >
> > Analyzed in XG Roller+
> > Player Winning Chances: 62.15% (G:30.88% B:4.85%)
> > Opponent Winning Chances: 37.85% (G:9.27% B:0.46%)
> >
> > Cubeless Equities: No Double=+0.498, Double=+0.772
> >
> > Cubeful Equities:
> > No redouble: +0.607
> > Redouble/Take: +0.328 (-0.280)
> > Redouble/Pass: +1.000 (+0.393)
> >
> > Best Cube action: No redouble / Take
> > Percentage of wrong pass needed to make the double decision right: 29.4%
> >
> > eXtreme Gammon Version: 2.10, MET: Kazaross XG2

It is not a money redouble.

Stick

Never look up when dragons fly overhead.

interests / rec.games.backgammon / A cube error

Subject	Author
A cube error	peps...@gmail.com
Re: A cube error	Timothy Chow
Re: A cube error	Stick Rice