"Standard" holding game but with an extra checker back

[Tim Chow]

XGID=-a---bEBC-C-cB----bbbba---:0:0:1:00:0:0:1:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Money session, Jacoby
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O O |
| X O | | O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | X |
| | | X |
| O X X | | X |
| O X X X | | X O |
| O X X X | | X O O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pipcount X: 124 O: 150 X-O: 0-0
Cube : 1
X on roll, cube action

---
Tim Chow

[badgolferman]

ND/Take

[Bradley K. Sherman]

Tim Chow <tchow...@yahoo.com> wrote:
>Score is X:0 O:0. Money session, Jacoby
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | X O | | O O O O |
> | X O | | O O O |
> | | | |
> | | | |
> | | | |
> | |BAR| |
> | | | X |
> | | | X |
> | O X X | | X |
> | O X X X | | X O |
> | O X X X | | X O O |
> +12-11-10--9--8--7-------6--5--4--3--2--1-+

> X:124 O:150, X on roll, cube action

ND/T

--bks

[Freeven]

Can O take? It looks like a trivial take to me.

Give X a good roll, say 62: 10/4 6/4, followed by a poorish roll by O,
say 21: 13/10. Can O still take. Looks like it to me.

N/T

[Tim Chow]

On May 4, 11:38 pm, Freeven <no...@nowhere.com> wrote:
> Give X a good roll, say 62: 10/4 6/4

In a holding game like this, a "good roll" usually means one that
clears the midpoint.

---
Tim Chow

[Freeven]

I'm not so sure. Looks to me that the lack of inner board landing places
is a bigger problem.

In any case, give X a great roll, one that improves in both areas, say
22: 13/11(2) 6/4(2). Can O still take? Looks close to me. And if I'm
right that O still has a take (or close to it) after X both clears the
midpoint and makes his four point, that suggests that it's too soon to
double.

[Walt]

On 5/4/2013 8:41 PM, Tim Chow wrote:

I've heard this defensive position of an anchor with a blot behind it on
the ace called a "stinger" or a "Scorpion"

With O's strong board and X having no board himself I don't think I'd
touch this as X. The take seems clear.

What about market losers? Other than big doubles (and I'm not even sure
about those) I'm not seeing any. So even if it is a double, it's
probably not much of an error to hold.

ND/T

//Walt

[Tim Chow]

Holding game vig is a combination of shot vig and racing vig. Here, O
is 26 pips down, which is not completely hopeless for the race, but
it's pretty bad, so she has to rely primarily on shot vig. In a
"standard" holding game with just a high anchor but no extra checker
guarding the rear, clearing the midpoint safely usually eliminates
most of the shot vig. When X has three landing points, as in this
position, O's shot vig usually isn't enough to allow her to take if
she's this far back in the race.

The extra checker back changes things. Sometimes the extra checker
back is an asset and sometimes it's a liability. It can provide more
shots, but it can also get attacked. In this position, X's naked
board and O's location on the 24pt imply that the blot is a clear
asset for O. It certainly provides more shots since it covers X's
home board, and it's too deep to be easily attacked.

I think Freeven had the right approach. If X gets a slightly lucky
roll that clears the midpoint, O can probably still take. See Variant
1 below. Given this, X has little reason to double now. Shift O's
straggler forwards two pips, though, and her chances deteriorate
significantly. See Variant 2 below, where the rollout indicates a
close take.

=======
Rollout
=======

No Double
Player Winning Chances: 68.54% (G: 8.85% B: 0.26%)
Opponent Winning Chances: 31.46% (G: 6.06% B: 0.13%)
Double/Take
Player Winning Chances: 69.04% (G: 8.65% B: 0.23%)
Opponent Winning Chances: 30.96% (G: 6.01% B: 0.13%)

Cubeful Equities:
No Double: +0.681
Double/Take: +0.606 (-0.075)
Double/Drop: +1.000 (+0.319)

Best Cube action: No Double / Take

Rollout
1296 Games rolled with Variance Reduction.
Dice Seed: 2
Moves and cube decisions: 3 ply
Confidence No Double: ±0.016 (+0.665<E<+0.697)
Confidence Double: ±0.021 (+0.584<E<+0.627)

=========
Variant 1
=========

XGID=-a---bECD-C-c-----bbbba---:0:0:1:00:0:0:1:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Money session, Jacoby
+13-14-15-16-17-18------19-20-21-22-23-24-+

| O | | O O O O |

| O | | O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | X |

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

Pipcount X: 113 O: 150 X-O: 0-0

Cube : 1
X on roll, cube action

Analyzed in Rollout
No Double
Player Winning Chances: 73.58% (G: 12.06% B: 0.21%)
Opponent Winning Chances: 26.42% (G: 3.86% B: 0.10%)
Double/Take
Player Winning Chances: 74.93% (G: 11.66% B: 0.09%)
Opponent Winning Chances: 25.07% (G: 3.89% B: 0.12%)

Cubeful Equities:
No Double: +0.873 (-0.099)
Double/Take: +0.972
Double/Drop: +1.000 (+0.028)

Best Cube action: Double / Take

Rollout
1296 Games rolled with Variance Reduction.
Dice Seed: 2
Moves and cube decisions: 3 ply
Confidence No Double: ±0.013 (+0.861<E<+0.886)
Confidence Double: ±0.028 (+0.944<E<+1.000)

=========
Variant 2
=========

XGID=---a-bEBC-C-cB----bbbba---:0:0:1:00:0:0:1:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Money session, Jacoby
+13-14-15-16-17-18------19-20-21-22-23-24-+
| X O | | O O O O |
| X O | | O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | X |
| | | X |
| O X X | | X |
| O X X X | | X O |
| O X X X | | X O O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+

Pipcount X: 124 O: 148 X-O: 0-0

Cube : 1
X on roll, cube action

Analyzed in Rollout
No Double
Player Winning Chances: 74.63% (G: 7.45% B: 0.14%)
Opponent Winning Chances: 25.37% (G: 2.91% B: 0.08%)
Double/Take
Player Winning Chances: 75.41% (G: 7.14% B: 0.08%)
Opponent Winning Chances: 24.59% (G: 2.80% B: 0.07%)

Cubeful Equities:
No Double: +0.921 (-0.039)
Double/Take: +0.961
Double/Drop: +1.000 (+0.039)

Best Cube action: Double / Take

Rollout
1843 Games rolled with Variance Reduction.
Dice Seed: 2
Moves and cube decisions: 3 ply
Confidence No Double: ±0.010 (+0.911<E<+0.931)
Confidence Double: ±0.013 (+0.947<E<+0.974)

eXtreme Gammon Version: 1.21

---
Tim Chow