A two-part problem

[peps...@gmail.com]

In the position below, it is obvious that I should double.
So my question 1 is why might I (a reasonably strong player)
go ahead and roll anyway without doubling when I'm playing XG?

Question 2 is where you get the chance to outsmart XG.
(How exciting!)
Here, I actually did double and XG blundered according to its own rollout.
Can you make the correct take/pass decision and thereby outplay XG?

(The answer is not that you should have two versions of XG and ask one of
them: "If I were to ask the other version of XG whether this is a take, what
would the other version say?" and then make the other play.)

Paul

XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
X:Daniel O:eXtremeGammon

Score is X:0 O:2. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X | | X O O O O O |
| X | | O O O O O |
| X | | O O O O |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | | +---+
| X X | | X X | | 4 |
| X X X | | X X X O | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 131 O: 66 X-O: 0-2
Cube: 4, X own cube
X on roll, cube action

[Timothy Chow]

On 8/14/2022 7:31 AM, peps...@gmail.com wrote:
> XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
> X:Daniel O:eXtremeGammon
>
> Score is X:0 O:2. Unlimited Game, Jacoby Beaver
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X | | X O O O O O |
> | X | | O O O O O |
> | X | | O O O O |
> | | | |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | X | | | +---+
> | X X | | X X | | 4 |
> | X X X | | X X X O | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 131 O: 66 X-O: 0-2
> Cube: 4, X own cube
> X on roll, cube action

I find these cube decisions difficult. O still has a five-point board
and a big lead in the pip count, and there is some chance X won't make
a five-prime right away. I'll take this one.

---
Tim Chow

[ah...Clem]

On 8/14/2022 7:31 AM, peps...@gmail.com wrote:

>

> XGID=--a-ABBCB-A--C-----Acccbc-:2:1:1:00:0:2:3:0:10
> X:Daniel O:eXtremeGammon
>
> Score is X:0 O:2. Unlimited Game, Jacoby Beaver
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X | | X O O O O O |
> | X | | O O O O O |
> | X | | O O O O |
> | | | |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | X | | | +---+
> | X X | | X X | | 4 |
> | X X X | | X X X O | +---+
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 131 O: 66 X-O: 0-2
> Cube: 4, X own cube
> X on roll, cube action

1) Looks like a pretty clear take since O has a strong board and a race
lead. Regardless, cubing gives your opponent a chance to make a mistake
while holding doesn't so I can't think of a reason to hold. Especially
since you say XG muffed the take.

2) See 1) above.

[peps...@gmail.com]

The reason I might hold is that, as I stated in another thread, I sometimes have trouble
with the XG app on my computer so I sometimes roll accidentally while trying to double.
It's incredibly annoying.

It's actually a clear pass, according to XG's rollout which is what I thought. I was surprised
by XG's take. I didn't say that XG muffed the take. I said that XG made the wrong decision.
XG wrongly took when it should have passed. However, XG's bad take was validated when
it beat me. My memory is that I rolled a 53 which I think is an excellent roll. We can't quite
call it a joker though because I'm a big fave to make the 5 point board. I played this 19/14 7/4
which I think is correct. XG rolled its miracle 61 to leap my prime. I then missed the triple shot and
XG doubled me out.
XG's board is currently strong but it's a big fave to weaken soon. XG does get more gammons than
I do, but only slightly more.

Analyzed in Rollout
No redouble
Player Winning Chances: 79.73% (G:4.21% B:0.06%)
Opponent Winning Chances: 20.27% (G:5.98% B:0.03%)
Redouble/Take
Player Winning Chances: 80.99% (G:4.67% B:0.11%)
Opponent Winning Chances: 19.01% (G:5.98% B:0.04%)

Cubeless Equities: No Double=+0.577, Double=+1.215

Cubeful Equities:
No redouble: +0.874 (-0.126)
Redouble/Take: +1.147 (+0.147)
Redouble/Pass: +1.000

Best Cube action: Redouble / Pass

Rollout:
1296 Games rolled with Variance Reduction.
Moves: 3-ply, cube decisions: XG Roller
Confidence No Double: ± 0.007 (+0.867..+0.881)
Confidence Double: ± 0.010 (+1.138..+1.157)

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

Duration: 18 minutes 04 seconds

eXtreme Gammon Version: 2.10

[Timothy Chow]

On 8/15/2022 3:25 PM, peps...@gmail.com wrote:
> It's actually a clear pass, according to XG's rollout which is what I thought.

Interesting. Even after I made some significant improvements to XG's
position, it rolled out to a pass:

XGID=-a--ABBCB-A--C----Accbbbb-:2:1:1:00:0:0:3:0:10

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 O O O |
| X | | O O O O O O |
| X | | O O |

| | | |
| | | |
| |BAR| |
| | | |
| | | |
| X | | | +---+
| X X | | X X | | 4 |
| X X X | | X X X O | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+

Pip count X: 130 O: 77 X-O: 0-0

Cube: 4, X own cube
X on roll, cube action

Analyzed in Rollout
No redouble

Player Winning Chances: 77.67% (G:3.92% B:0.06%)
Opponent Winning Chances: 22.33% (G:6.34% B:0.08%)
Redouble/Take
Player Winning Chances: 79.09% (G:4.59% B:0.12%)
Opponent Winning Chances: 20.91% (G:6.97% B:0.08%)

Cubeful Equities:
No redouble: +0.818 (-0.182)
Redouble/Take: +1.055 (+0.055)

Redouble/Pass: +1.000

Best Cube action: Redouble / Pass

Rollout:
1296 Games rolled with Variance Reduction.

Dice Seed: 271828

Moves: 3-ply, cube decisions: XG Roller

Confidence No Double: ± 0.006 (+0.812..+0.824)
Confidence Double: ± 0.011 (+1.044..+1.065)

eXtreme Gammon Version: 2.19.207.pre-release

[peps...@gmail.com]

Our position is obviously stronger than it appears to you and Walt.
One consideration is that it's very hard for XG to hit a shot on XG's next roll.
That fact is reflected in XG's low gammon count. I think that 55 is our only roll which
concedes a direct shot.
When superficially similar positions are takes, it's often because the opponent has already
removed a checker and therefore can't lose a gammon.
I'm sure you can readily get takes by variantizing that way.
As far as I can see, XG's good scenario is that 1) I fail to make the 5 prime. 2) XG leaps.
3) I miss the shot.

That's quite a parlay -- I'm surprised these aren't even bigger passes than they are.

Paul

[Timothy Chow]

On 8/16/2022 12:23 PM, peps...@gmail.com wrote:
> As far as I can see, XG's good scenario is that 1) I fail to make the 5 prime. 2) XG leaps.
> 3) I miss the shot.

Because the pip count lead is so large, XG has multiple
opportunities to leap your five-prime. If you hit loose
then XG could hit back and leap your prime when you're
dancing. If XG leaps and you hit, it could leap a second
time.

---
Tim Chow