The ballad of rgb

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peps...@gmail.com

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Sep 9, 2021, 6:29:06 PMSep 9
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I know not if my cube is weak
Or if my cube be strong.
All that we at rgb know
is that Paul's formatting's often wrong.

XGID=-a----EBDaB-bBa--abeb-----:0:0:1:00:1:0:3:0X:Daniel O:eXtremeGammon
:10

Score is X:1 O:0. Unlimited Game, Jacoby Beaver
+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 |
| |BAR| |
| | | X |
| X | | X |
| X | | X |
| O X X X | | X |
| O X O X X | | X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 122 O: 139 X-O: 1-0
Cube: 1
X on roll, cube action


Timothy Chow

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Sep 10, 2021, 9:50:55 PMSep 10
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With X having no board and a somewhat inflexible position, I would
certainly take this as O. As for the double, I don't think most
hitting rolls lose X's market. But maybe if X makes a good point
and O fails to hit? I don't think I'd double OTB but this could
be a double.

---
Tim Chow

peps...@gmail.com

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Sep 11, 2021, 4:43:06 AMSep 11
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Actually, it rolled out to a close pass.
I kept the details carefully on my other computer, so I'll post the rollout today.
I had a similar reaction OTB to you, in that I had trouble deciding whether to double or not.
Fortunately, I decided to double.

Paul

peps...@gmail.com

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Sep 11, 2021, 6:58:32 AMSep 11
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Analyzed in Rollout
No double
Player Winning Chances: 75.10% (G:11.89% B:0.33%)
Opponent Winning Chances: 24.90% (G:3.63% B:0.12%)
Double/Take
Player Winning Chances: 75.20% (G:12.85% B:0.42%)
Opponent Winning Chances: 24.80% (G:3.90% B:0.16%)

Cubeless Equities: No Double=+0.587, Double=+1.192

Cubeful Equities:
No double: +0.865 (-0.135)
Double/Take: +1.033 (+0.033)
Double/Pass: +1.000

Best Cube action: Double / Pass

Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: ± 0.007 (+0.858..+0.872)
Confidence Double: ± 0.013 (+1.020..+1.046)

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

Duration: 42 minutes 39 seconds

eXtreme Gammon Version: 2.10

Timothy Chow

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Sep 12, 2021, 12:57:34 PMSep 12
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On 9/11/2021 4:43 AM, peps...@gmail.com wrote:
> Actually, it rolled out to a close pass.
> I kept the details carefully on my other computer, so I'll post the rollout today.
> I had a similar reaction OTB to you, in that I had trouble deciding whether to double or not.
> Fortunately, I decided to double.

With hindsight, I can offer the following line of reasoning.

What if O's two rearmost checkers were anchored on X's 5pt?
Then it would be a fairly standard D/T. Splitting O's checkers
can't be good for O, so it must still be a double, with the
take in question.

---
Tim Chow

peps...@gmail.com

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Sep 13, 2021, 4:03:47 AMSep 13
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An excellent way of thinking about it.
With that thought experiment, it might be a surprise that the pass is so marginal.

However, I think that human intuition is suspect when it concerns decisions that are never made
in practice. We can't move our checkers backwards. So when we're anchored on the 5 point, we never
need to think about whether we would rather have one checker on the opponent's ace point and the other on their
9 point. When you compare the two variants, many parlays work much better for the favourite when the opponent
is anchored.
Did you variantize here?
I wouldn't be surprised if your variant is actually a pass too(?)
Getting past the opponent's 5 point anchor is easier than usual in the variant, because there are so many landing spots
for the midpoint checkers.

Paul
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