XGID=-A-D--A------------a-ba-b-:1:-1:-1:00:0:0:0:5:10

X:X O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O |
| | | O |
| | | O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | | +---+
| | | X X | | 2 |
| | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 19 O: 19 X-O: 0-0/5
Cube: 2, X own cube
X on roll, cube action

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"ah...Clem" <ah_clem@ymail.com> writes:

XGID=-A-D--A------------a-ba-b-:1:-1:-1:00:0:0:0:5:10

X:X O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O |
| | | O |
| | | O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | | +---+
| | | X X | | 2 |
| | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 19 O: 19 X-O: 0-0/5
Cube: 2, X own cube
X on roll, cube action

Opponents match equity (all with Turner's formula) after R/P:

50 - (24/5 + 3)*2 = 34

After R/T and a loss:

50 - (24/5 + 3)*4 = 19

After R/T and a win:

81 (due to symmetry to the case above)

Opponents take point is risk/(risk + reward):

(34 - 19)/(34 - 19 + (81 - 34)) =
15/62 = 24

Winning percentage with Isight:

80 - 19/3 + 2*(21 - 19) =

77

D/P

All rounded and without recube vigorish, which might warrant a take.

Very much interested in Paul's detailed mental arithmetic!

And side note for accuracy fetishists:

- With me a 50 ELO better player it is D/T and D/P wrong by 0.04
- With me a 50 ELO weaker player it is D/P and D/T wrong by 0.17

First rule of doubling: Know your opponent.

Axel

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Perhaps this is too simple a position for the group, but I'm genuinely perplexed. A recube to 4 at 5a5a has a live takepoint of 24%, and since
there are no gammons possible this should be the baseline for the take.

Does O have 24% GWC? According to the rollout, she has a 25% chance,
which should imply a take. But taking here is a whopper. What gives?


Is it because O rarely gets a recube? There's only two to four rolls to
turn it around, so perhaps that's it. Or am I missing something?


XGID=-A-D--A------------a-ba-b-:1:-1:-1:00:0:0:0:5:10

X:Player 2 O:Player 1
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O |
| | | O |
| | | O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | | +---+
| | | X X | | 2 |
| | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 19 O: 19 X-O: 0-0/5
Cube: 2, X own cube
X on roll, cube action

Analyzed in Rollout
No redouble
Player Winning Chances: 74.99% (G:0.00% B:0.00%)
Opponent Winning Chances: 25.01% (G:0.00% B:0.00%)
Redouble/Take
Player Winning Chances: 74.99% (G:0.00% B:0.00%)
Opponent Winning Chances: 25.01% (G:0.00% B:0.00%)

Cubeless Equities: No Double=+0.500, Double=+1.155

Cubeful Equities:
No redouble: +0.750 (-0.250)
Redouble/Take: +1.112 (+0.112)
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: ± 0.001 (+0.749..+0.751)
Confidence Double: ± 0.002 (+1.110..+1.113)

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

Duration: 1.2 seconds

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

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On 8/30/2022 2:48 PM, Axel Reichert wrote:

"ah...Clem" <ah_clem@ymail.com> writes:

XGID=-A-D--A------------a-ba-b-:1:-1:-1:00:0:0:0:5:10

X:X O:O
Score is X:0 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O |
| | | O |
| | | O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | | +---+
| | | X X | | 2 |
| | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 19 O: 19 X-O: 0-0/5
Cube: 2, X own cube
X on roll, cube action

Calculations snipped

81 (due to symmetry to the case above)

Opponents take point is risk/(risk + reward):

(34 - 19)/(34 - 19 + (81 - 34)) =
15/62 = 24

Yes, that agrees with XG's cube information.

Winning percentage with Isight:

77

XG rollout says 75%

D/P

XG agrees with this result, but it implies that the takepoint is 24%,
and it's a pass at 25%.

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On 9/1/2022 10:09 AM, ah...Clem wrote:

Perhaps this is too simple a position for the group, but I'm genuinely perplexed. A recube to 4 at 5a5a has a live takepoint of 24%, and since there are no gammons possible this should be the baseline for the take.

Does O have 24% GWC? According to the rollout, she has a 25% chance,
which should imply a take. But taking here is a whopper. What gives?

I feel like I've said this many times before, but "live cube takepoint"
is black magic hocus pocus. I wouldn't trust it. The "dead cube
takepoint" has a sound theoretical basis. In this position, it's 28%,
which would indicate a drop. The question is whether the taker has
enough recube vig to bring that 28% figure down below 25%. Apparently,
the answer is no. As you say, a correct recube to 8 is rare in this
position.

---
Tim Chow

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Timothy Chow <tchow12000@yahoo.com> writes:

"live cube takepoint" is black magic hocus pocus. I wouldn't trust
it.

Tim, is it you? Or has some Compuserve user faked your address? (-;

The question is whether the taker has enough recube vig to bring that
28% figure down below 25%.

And the question is how to quantify recube vigorish (over the board) ...

Best regards

Axel

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On 9/2/2022 9:56 AM, I wrote:

Xavier did comply with my request to include relevant raw data
from a rollout.  In a sufficiently recent version of XG, if you
right-click on a move after rolling it out, one option is to
"Display Rollout Stats..." which will tell you about how often
the cube is turned again in subsequent play.  For example, in this
position, you'll find that the opponent gets in a RD/P about 15%
of the time and a RD/T about 4% of the time.

I just tried rolling it out for money. RD/P happens about 16% of
the time and RD/T only about 1% of the time. But I think a key
difference is that the gain from a correct redouble is less ATS
than for money. If you didn't redouble ATS then you'd still be
ahead 5a Crawford anyway when you win.

---
Tim Chow

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On 9/2/2022 1:45 AM, Axel Reichert wrote:

Timothy Chow <tchow12000@yahoo.com> writes:

"live cube takepoint" is black magic hocus pocus. I wouldn't trust
it.

Tim, is it you? Or has some Compuserve user faked your address? (-;

The question is whether the taker has enough recube vig to bring that
28% figure down below 25%.

And the question is how to quantify recube vigorish (over the board) ...

The same way we do anything over the board...through experience.
But the bots could help by providing more information about such
things, instead of quoting some mysterious one-size-fits-all (or
maybe one-size-fits-none) "live cube takepoint."

Xavier did comply with my request to include relevant raw data
from a rollout. In a sufficiently recent version of XG, if you
right-click on a move after rolling it out, one option is to
"Display Rollout Stats..." which will tell you about how often
the cube is turned again in subsequent play. For example, in this
position, you'll find that the opponent gets in a RD/P about 15%
of the time and a RD/T about 4% of the time.

---
Tim Chow

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