GNU Backgammon Position ID: 4Bw8oFSM18GAEg
Match ID : cAlgAXAAMAAE
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
| X X X O | O | O X | 7 points
| O | | O X |
| O | | O |
| | | |
| | | |
| |BAR| |v 11 point match (Cube: 1)
| | | |
| X | | O |
| X | | X O |
| X X | | X O | On roll
| O O X O O X | | X X O | 6 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: axel
Pip counts: O 207, X 151

On 12/22/2022 3:10 PM, Axel Reichert wrote:
> GNU Backgammon Position ID: 4Bw8oFSM18GAEg
> Match ID : cAlgAXAAMAAE
> +24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
> | X X X O | O | O X | 7 points
> | O | | O X |
> | O | | O |
> | | | |
> | | | |
> | |BAR| |v 11 point match (Cube: 1)
> | | | |
> | X | | O |
> | X | | X O |
> | X X | | X O | On roll
> | O O X O O X | | X X O | 6 points
> +-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: axel
> Pip counts: O 207, X 151

X looks to me to have a massive advantage here. He's over 50 pips up
and has ten checkers in the zone. At 5a4a his gammon value is elevated.
O's main saving grace is that she has a pretty good chance of anchoring,
but that seems like relatively weak compensation. I would pass as O.

Is it too good? Maybe, but if she gets a high anchor then I think she
can take. D/P is my guess.

---
Tim Chow

On Thursday, December 22, 2022 at 8:09:44 PM UTC-5, Tim Chow wrote:
> On 12/22/2022 3:10 PM, Axel Reichert wrote:
> > GNU Backgammon Position ID: 4Bw8oFSM18GAEg
> > Match ID : cAlgAXAAMAAE
> > +24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
> > | X X X O | O | O X | 7 points
> > | O | | O X |
> > | O | | O |
> > | | | |
> > | | | |
> > | |BAR| |v 11 point match (Cube: 1)
> > | | | |
> > | X | | O |
> > | X | | X O |
> > | X X | | X O | On roll
> > | O O X O O X | | X X O | 6 points
> > +-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: axel
> > Pip counts: O 207, X 151
> X looks to me to have a massive advantage here. He's over 50 pips up
> and has ten checkers in the zone. At 5a4a his gammon value is elevated.
> O's main saving grace is that she has a pretty good chance of anchoring,
> but that seems like relatively weak compensation. I would pass as O.
>
> Is it too good? Maybe, but if she gets a high anchor then I think she
> can take. D/P is my guess.
>
> ---
> Tim Chow

Maybe it's what you meant but it's not entirely clear from how you said it. 5a has an elevated gammon value on a 2 cube, not a centered cube. Normally you wouldn't have to stipulate but if you're considering a position as TG or not also it needs to be clarified.

Stick

On 12/22/2022 11:41 PM, Stick Rice wrote:
> Maybe it's what you meant but it's not entirely clear from how you said it. 5a has an elevated gammon value on a 2 cube, not a centered cube. Normally you wouldn't have to stipulate but if you're considering a position as TG or not also it needs to be clarified.

What you say is correct, of course, but whether a cube decision is
TG (or not) is not particularly sensitive to the gammon value on the
current value of the cube. For example, unless this position is
just borderline TG, I'd expect that the answer to the "TG or not"
question for this position would be the same at 4a4a as at 5a4a,
even though it's surely a much bigger pass at 4a4a than at 5a4a.

---
Tim Chow

Axel Reichert <mail@axel-reichert.de> writes:

> GNU Backgammon Position ID: 4Bw8oFSM18GAEg
> Match ID : cAlgAXAAMAAE
> +24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
> | X X X O | O | O X | 7 points
> | O | | O X |
> | O | | O |
> | | | |
> | | | |
> | |BAR| |v 11 point match (Cube: 1)
> | | | |
> | X | | O |
> | X | | X O |
> | X X | | X O | On roll
> | O O X O O X | | X X O | 6 points
> +-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: axel
> Pip counts: O 207, X 151

Big double, big pass. Far from too good. Over the board I kept the cube,
my judgement was impaired by the many blots (4 each): "Too much play in
this game I thought" and missed the fact that Position, Race And Threats
all point to a double and, with 3:0 criteria, to a pass as well.

Cube analysis
Rollout cubeless equity +0.693 (Money: +0.673)

Cubeful equities:
1. Double, pass +1.000
2. Double, take +1.290 (+0.290)
3. No double +0.875 (-0.125)
Proper cube action: Double, pass

Rollout details:
Centered 1-cube:
0.636 0.398 0.069 - 0.364 0.065 0.003 CL +0.693 CF +0.875
[0.000 0.001 0.000 - 0.000 0.000 0.000 CL 0.002 CF 0.002]
Player gnubg owns 2-cube:
0.637 0.397 0.068 - 0.363 0.065 0.003 CL +1.666 CF +1.290
[0.001 0.001 0.001 - 0.001 0.000 0.000 CL 0.005 CF 0.005]
Truncated cubeful rollout (depth 6) with variance reduction
1474 games, Mersenne Twister dice gen. with seed 445148145 and quasi-random dice
Stop when std.errs. are small enough: limit 0.0050 (min. 36 games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity 0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
Different evaluations after 2 plies:
Play: 1-ply cubeful
keep the first 0 0-ply moves and up to 8 more moves within equity 0.16
Cube: 2-ply cubeful prune [world class]
Output generated Sat Dec 24 14:19:59 2022
by GNU Backgammon 1.06.002 Nov 19 2020 (Text Export version 1.114)