Crunch time 3

Tim Chow

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Dec 29, 2015, 7:06:18 PM12/29/15

to

XGID=--BaBBBCB-------bc-cdbB---:0:0:1:62:0:0:0:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O O | | O O O X |
| O O | | O O O X |
| O | | O O |
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| X | | |
| X X | | X X X X |
| X X | | X X X O X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 115 O: 110 X-O: 0-0
Cube: 1
X to play 62

---
Tim Chow

Bradley K. Sherman

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Dec 29, 2015, 7:36:32 PM12/29/15

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

> X:115 O:110, Cube:1, X to play 62

7/1,7/5 ??

--bks

Chase

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Dec 29, 2015, 7:40:59 PM12/29/15

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7/1 7/5 feels best to me, and I'm not sure why. It keeps the prime as
extended as possible, and keeps O's 5s blocked, which don't play nicely
for him otherwise. It's also allows me to cover my 1pt with a 6 next
turn without leaving a blot most of the time. But that's rationalizing
after the fact. Sometimes you make a play just because it feels right.

7/1 7/5

michae...@gmail.com

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Dec 30, 2015, 4:57:42 AM12/30/15

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I don't think any tricks would work here. 7/1 7/5?? Suppose she gets stuck what do we gain? 4s are duplicated both for escaping and making the 3pt. And if we get hit we are dead meat.
7/1 4/2?? Looks worse
How about the pedestrian move 8/6 8/2? Well at least it keeps the race equal, although something tells me one of the previous moves might be the answer.
I will go for the pedestrian move
8/6 8/2

michae...@gmail.com

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Dec 30, 2015, 5:05:03 AM12/30/15

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I meant to ask this before but I forgot.
Tim, are you posting your quizes for each series, in an increasing degree of difficulty?

Tim Chow

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Dec 30, 2015, 11:11:35 PM12/30/15

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No. And even if I were to try, I don't think I would succeed. What is easy
for one person is hard for another.

---
Tim Chow

Tim Chow

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Dec 31, 2015, 7:08:41 PM12/31/15

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I still don't fully understand this one. One advantage of 7/5 7/1 or 8/6 7/1
is that it gives X better offensive chances if O rolls poorly.

However, I still don't quite understand why the computer says that 8/6 8/2
is a whopper, yet in the variant position with X's anchor on the 2pt instead
of the 3pt, 8/6 8/2 comes out on top. I'll try posting to BGOnline to see if
anyone there has any insights.

1. Rollout¹ 7/5 7/1 eq:-0.627
Player: 31.79% (G:5.11% B:0.09%)
Opponent: 68.21% (G:9.25% B:0.28%)
Confidence: ±0.010 (-0.637..-0.617) - [99.3%]

2. Rollout¹ 8/6 7/1 eq:-0.643 (-0.016)
Player: 31.51% (G:4.57% B:0.07%)
Opponent: 68.49% (G:9.19% B:0.29%)
Confidence: ±0.008 (-0.650..-0.635) - [0.7%]

3. Rollout¹ 8/6 8/2 eq:-0.721 (-0.094)
Player: 30.86% (G:3.54% B:0.07%)
Opponent: 69.14% (G:8.05% B:0.23%)
Confidence: ±0.009 (-0.730..-0.711) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.208.pre-release

-------
Variant
-------

XGID=--BaBBBCB-------bc-cdb-B--:0:0:1:62:0:0:0:0:10

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

Pip count X: 117 O: 110 X-O: 0-0

Cube: 1
X to play 62

1. Rollout¹ 8/6 8/2 eq:-0.841
Player: 28.01% (G:3.79% B:0.10%)
Opponent: 71.99% (G:10.78% B:0.40%)
Confidence: ±0.012 (-0.853..-0.829) - [50.0%]

2. Rollout¹ 8/6 7/1 eq:-0.885 (-0.044)
Player: 27.82% (G:4.11% B:0.07%)
Opponent: 72.18% (G:12.40% B:0.53%)
Confidence: ±0.014 (-0.899..-0.871) - [50.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.208.pre-release

---
Tim Chow

michae...@gmail.com

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Jan 4, 2016, 2:35:57 AM1/4/16

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On Friday, January 1, 2016 at 2:08:41 AM UTC+2, Tim Chow wrote:
> XGID=--BaBBBCB-------bc-cdbB---:0:0:1:62:0:0:0:0:10
>
> X:Player 1 O:Player 2
> Score is X:0 O:0. Unlimited Game
> +13-14-15-16-17-18------19-20-21-22-23-24-+
> | O O | | O O O X |
> | O O | | O O O X |
> | O | | O O |
> | | | O |
> | | | |
> | |BAR| |
> | | | |
> | | | |
> | X | | |
> | X X | | X X X X |
> | X X | | X X X O X |
> +12-11-10--9--8--7-------6--5--4--3--2--1-+
> Pip count X: 115 O: 110 X-O: 0-0
> Cube: 1
> X to play 62
>
> I still don't fully understand this one. One advantage of 7/5 7/1 or 8/6 7/1
> is that it gives X better offensive chances if O rolls poorly.
>
> However, I still don't quite understand why the computer says that 8/6 8/2
> is a whopper, yet in the variant position with X's anchor on the 2pt instead
> of the 3pt, 8/6 8/2 comes out on top. I'll try posting to BGOnline to see if
> anyone there has any insights.
>

Had I paid more attention noticing X holds the 3 point anchor,I'd probably have found the right answer for this. Notice the difficulties this anchor causes to O, and the fact that if we get hit and recirculate a checker it's not that bad.
I still hold my old view about the 3pt anchor been the most defending one/ causing most trouble to the opponent... O's 5s are problematic at this position,
imo you should not see 7/5 7/1 imo as such a great move, it's just that playing 8/6 8/2 scraps whatever benefits you already have from your 3pt anchor.