FIBS Board backgammon forum
Backgammon => Fibsboard Forum Matches => FFM 20 => Topic started by: stog on October 11, 2014, 09:15:48 AM
roman would you like a cube?
Despite the gammon danger, i think this is a trivial take, i guess i will win 1 game out of 3; even pip count, no checker out of play, and you still have one man back; so i take this cube.
Always a take, the herd's four blots mean that roman can get back into this very quickly, but the double decision is interesting. Not technically a cube here because of the score, a strong cube if the scores were reversed, but in a match a double is a good practical play. It costs you a tenth of a point in equity, but there is a triple whammy that pays for this. First you may get a bad pass and 16% chance of a pass here is enough to justify the cube on its own. Second, it means that you can't make a doubling mistake later and if you don't cube, you will certainly have some more decisions to make. Thirdly, your opponent holding the cube may well make one or more mistakes with recube decisions! Sometimes it's good to do something, even when it is wrong.
rollout
Spoiler
The take is trivial, although I'm sure there are some who will pass. AtS it's a whopper to push the cube, but as Dorbel points out there are some practical reasons why it's not as bad as it seems. At a "normal" score (see variant) the cube decision is too close to call, but being ahead 2-0 to 7 we need to be a bit more stingy with the cube.
XGID=a---BBC-A--AdD-A-cbe----A-:0:0:1:00:2:0:0:7:10
X:Player 1 O:Player 2
Score is X:2 O:0 7 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X X O O | | O X |
| X O O | | O |
| X O | | O |
| X | | O |
| | | O |
| |BAR| |
| | O | |
| O | | |
| O | | X |
| O | | X X X |
| O X X | | X X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 146 O: 145 X-O: 2-0/7
Cube: 1
X on roll, cube action
Analyzed in Rollout
No double
Player Winning Chances: 64.74% (G:21.50% B:0.49%)
Opponent Winning Chances: 35.26% (G:7.05% B:0.30%)
Double/Take
Player Winning Chances: 65.09% (G:21.35% B:0.55%)
Opponent Winning Chances: 34.91% (G:7.36% B:0.60%)
Cubeless Equities: No Double=+0.430, Double=+0.862
Cubeful Equities:
No double: +0.566
Double/Take: +0.454 (-0.112)
Double/Pass: +1.000 (+0.434)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 17.0%
Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: ± 0.012 (+0.553..+0.578)
Confidence Double: ± 0.017 (+0.436..+0.471)
Double Decision confidence: 100.0%
Take Decision confidence: 100.0%
Duration: 10 minutes 58 seconds
eXtreme Gammon Version: 2.10, MET: Kazaross XG2
///////////////////money play, no jacoby//////////////////
XGID=a---BBC-A--AdD-A-cbe----A-:0:0:1:00:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X X O O | | O X |
| X O O | | O |
| X O | | O |
| X | | O |
| | | O |
| |BAR| |
| | O | |
| O | | |
| O | | X |
| O | | X X X |
| O X X | | X X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 146 O: 145 X-O: 0-0
Cube: 1
X on roll, cube action
Analyzed in XG Roller++
Player Winning Chances: 64.87% (G:20.58% B:0.41%)
Opponent Winning Chances: 35.13% (G:6.76% B:0.26%)
Cubeless Equities: No Double=+0.437, Double=+0.892
Cubeful Equities:
No double: +0.639
Double/Take: +0.635 (-0.004)
Double/Pass: +1.000 (+0.361)
Best Cube action: No double / Take
Percentage of wrong pass needed to make the double decision right: 1.1%
eXtreme Gammon Version: 2.10