On Sunday, October 31, 2021 at 10:58:27 PM UTC, Tim Chow wrote:
On 10/29/2021 5:11 PM, peps...@gmail.com wrote:
Farewell, farewell thou Wedding Guest
Be thou not afraid.
He blitzeth best who doubleth best.
Whether money or match be played.
What cube action would the Ancient Mariner have recommended here?
Paul
XGID=ab-BBaB-CA-Ab-----BcbbbAA-:1:1:1:00:2:0:3:X:Daniel O:eXtremeGammon 0:10
Score is X:2 O:0. Unlimited Game, Jacoby Beaver +13-14-15-16-17-18------19-20-21-22-23-24-+
| X | | O O O O X X |
| X | | O O O O |
| | | O |
| | | |
| | | |
| |BAR| |
| | O | |
| | | |
| X | | | +---+
| O X | | X X X O | | 2 |
| O X X X | | X O X X O | +---+ +12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 153 O: 161 X-O: 2-0
Cube: 2, X own cube
X on roll, cube action
I would take this one. O has a strong board and X still has two
stragglers, so O retains good winning chances even though X has
good gammon chances. But if X hits and O fails to hit back then
I think X loses his market. D/T for me.
I doubled this one quite confidently, although, like you, I expected the take. It's interesting that you see this as a take/pass problem rather than a double/hold problem. I thought (wrongly) that both actions were equally clear. Note that, if this was primarily a take/pass problem, the Mariner's verse would make
no sense (but maybe it makes no sense anyway) because the Mariner is making an (admittedly obvious) point
about blitzing, not defending against the blitz. (Or maybe I'm wrong to think this is a blitz as the opponent
is anchored. But I don't think so. Blitzing means you aim to bring your checkers round to a winning position
while your opponent is dancing -- a likely outcome here.)
XG sees this (and I don't doubt it) as ND/T. This is surprising (to me and Tim) for a volatile position
with our equity above 0.6 -- I'm sure there are plenty of market losers.
In retrospect, the hold is probably because most of the market losers don't lead to terribly inefficient cubes
(perhaps something like 1.2 passes is typical), and also because there are plenty of bad sequences
where the opponent's cube ownership really hurts.
I bet it's a big cube when the cube is centred but I have difficulty setting up the positions so I'm not
going to variantize this.
Paul
Analyzed in Rollout
No redouble
Player Winning Chances: 63.64% (G:29.99% B:3.49%)
Opponent Winning Chances: 36.36% (G:14.01% B:1.22%)
Redouble/Take
Player Winning Chances: 63.40% (G:30.10% B:3.89%)
Opponent Winning Chances: 36.60% (G:14.17% B:1.15%)
Cubeless Equities: No Double=+0.455, Double=+0.909
Cubeful Equities:
No redouble: +0.665
Redouble/Take: +0.616 (-0.049)
Redouble/Pass: +1.000 (+0.335)
Best Cube action: No redouble / Take
Percentage of wrong pass needed to make the double decision right: 11.4%
Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: ± 0.014 (+0.651..+0.679)
Confidence Double: ± 0.026 (+0.590..+0.641)
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
Duration: 48 minutes 11 seconds
eXtreme Gammon Version: 2.10
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