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Backgammon => Fibsboard Forum Matches => FFM 18 => Topic started by: stiefnu on May 26, 2014, 12:05:33 PM

Poll
Question:
Option 1: 5-off, 5-2*
Option 2: 5-off, 3-off
Option 3: 5-off, 4-1
Title: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: stiefnu on May 26, 2014, 12:05:33 PM
So, the Herd now rolls 53 and is bound to leave a shot. How should we play this one, hit or not?

5-pt match, juanz 0-4 Herd, Crawford
Pipcount: juanz (red) 58, Herd (black) 29

Steve
Title: Re: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: Julia_H on May 27, 2014, 09:20:27 AM
Spoiler
Rip two. The immediate risk is the same either way, the extra man off makes the race that bit more favourable, and if we don't then the blot on 2 won't be easy to cover after a dance.
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Title: Re: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: stiefnu on May 27, 2014, 10:43:51 AM
Rollout

Spoiler
BGBlitz preferred the hit over ripping two, with match winning probabilities of 0.961 and 0.959 respectively.
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Steve
Title: Re: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: dorbel on May 27, 2014, 11:01:11 AM
Spoiler
Two men off doesn't save a roll and it leaves the man on the 2pt to be a future threat. If you hit, then the rolls where red dances are a nuisance, but no worse than if you leave him on the 2pt. Best of all, if you hit, then his sixes and fives force him to leave. Hitting looks right to me.
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Title: Re: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: ah_clem on May 27, 2014, 03:07:07 PM
Spoiler

Sorry I missed the vote yesterday.

Usually hitting is correct here. If he rolls a 5 or a 6 he's out of our hair for good.  And with an odd number of checkers to bear off ripping off two doesn't save a roll.

If we had one more or one less checker off it would be a tougher decision, but i think i'd still hit.

5/off 5/3 for me.
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Title: Re: Fibsboard Forum Match 18 Game 4 Move 42 Herd to move
Post by: ah_clem on May 27, 2014, 03:16:51 PM

Rollout

Spoiler
Quote from: stiefnu on May 27, 2014, 10:43:51 AM
BGBlitz preferred the hit over ripping two, with match winning probabilities of 0.961 and 0.959 respectively.

Steve

Interesting. XG full rollout says ripping off two is better by a very small margin.




XGID=-BaCBB-------a--------dbg-:0:0:1:53:4:0:1:5:10

X:Player 1   O:Player 2
Score is X:4 O:0 5 pt.(s) match.
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O                |   |          O  O  O |
|                  |   |          O  O  O |
|                  |   |          O     O |
|                  |   |          O     O |
|                  |   |                7 |
|                  |BAR|                  |
|                  |   |                  |
|                  |   |                  |
|                  |   |          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: 29  O: 58 X-O: 4-0/5 Crawford
Cube: 1
X to play 53

    1. Rollout¹    5/Off 3/Off                  eq:+0.953
      Player:   97.66% (G:23.75% B:0.49%)
      Opponent: 2.34% (G:0.00% B:0.00%)
      Confidence: ±0.001 (+0.952..+0.955) - [100.0%]
      Duration: 11.3 seconds

    2. Rollout¹    5/Off 5/2*                   eq:+0.945 (-0.008)
      Player:   97.25% (G:22.82% B:0.38%)
      Opponent: 2.75% (G:0.00% B:0.00%)
      Confidence: ±0.001 (+0.944..+0.946) - [0.0%]
      Duration: 8.6 seconds

    3. 3-ply       5/Off 4/1                    eq:+0.832 (-0.122)
      Player:   91.58% (G:8.96% B:0.08%)
      Opponent: 8.42% (G:0.00% B:0.00%)


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


eXtreme Gammon Version: 2.10, MET: Kazaross XG2


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