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Rollout Result and Brief Commentary

Posted By: Paul Weaver
Date: Friday, 30 December 2016, at 6:25 a.m.

In Response To: Gammon Save Checker Play 32 (Paul Weaver)

When this came up in a similar-to-money situation, I was way wrong in staying on the 20pt. I wondered how far wrong it might be to make the 18pt at gammon save, and I found a variation (posted below) in which the 18pt play wins the gammon-save rollout.

Let's take a look at the probability distributions of the two plays. The PD of the first (second) play is found on the 2nd and 3rd (5th and 6th) lines of the rollout data below. (I know that this ugly mess of digits in the rollout data is boring and even frightening, but sometimes illuminating info can be gleaned from studying these numbers.) Making the 18pt increases Blue's wins by 8.53% (from 29.63 to 38.16) while also increasing his gammon losses by 8.22% (from 5.11 to 13.33).

8.53 is bigger than 8.22, so making the 18pt increases your wins a bit more than it decreases your gammon losses. Therefore, at the gammon-save gammon price of 1.0, Blue should make the 18pt. At any other score with a lower gammon price, the 18pt play should win the rollout by a bigger margin than we see here.

One detail I hope nobody will ask me is how to estimate these 8.53 and 8.22 numbers in your head over the board while the clock is running. I admit I have not yet learned how to do this.

		White is White score: 0 pip: 108 2 point match Crawford pip: 116 score: 1 Blue is Blue
XGID=-B-BB-C-C---b--bbcAbB-b-b-:0:0:1:32:1:0:1:2:10
Blue to play 32

1.	Rollout1	20/18 8/5	eq: -0.503
	Player: Opponent: 38.16% (G:8.76% B:0.23%) 61.84% (G:13.33% B:0.51%) Conf.: ± 0.001 (-0.504...-0.502) - [100.0%] Duration: 46 minutes 40 seconds
2.	Rollout1	8/3	eq: -0.510 (-0.006)
	Player: Opponent: 29.63% (G:3.95% B:0.07%) 70.37% (G:5.11% B:0.21%) Conf.: ± 0.001 (-0.510...-0.509) - [0.0%] Duration: 50 minutes 08 seconds
3.	Rollout2	8/6 8/5	eq: -0.528 (-0.025)
	Player: Opponent: 30.36% (G:5.62% B:0.08%) 69.64% (G:6.75% B:0.41%) Conf.: ± 0.004 (-0.532...-0.524) - [0.0%] Duration: 2 minutes 12 seconds
4.	4-ply	8/5 6/4	eq: -0.543 (-0.040)
	Player: Opponent: 28.76% (G:4.02% B:0.05%) 71.24% (G:5.92% B:0.14%)
5.	3-ply	20/18 6/3	eq: -0.546 (-0.043)
	Player: Opponent: 33.87% (G:4.47% B:0.06%) 66.13% (G:11.19% B:0.15%)
6.	3-ply	6/1	eq: -0.573 (-0.070)
	Player: Opponent: 27.51% (G:3.25% B:0.05%) 72.49% (G:6.16% B:0.10%)
1 20736 Games rolled with Variance Reduction. Dice Seed: 101 Moves: 3-ply, cube decisions: XG Roller 2 1296 Games rolled with Variance Reduction. Dice Seed: 101 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

Messages In This Thread

• Gammon Save Checker Play 32
  Paul Weaver -- Thursday, 29 December 2016, at 5:57 p.m.
  • Gammon Save Checker Play 32
    gudgen -- Thursday, 29 December 2016, at 6:43 p.m.
    • Comment for gudgen
      Paul Weaver -- Thursday, 29 December 2016, at 7:28 p.m.
      • Comment for gudgen
        gudgen -- Thursday, 29 December 2016, at 11:53 p.m.
  • Gammon Save Checker Play 32
    TraumaBG -- Thursday, 29 December 2016, at 7:53 p.m.
    • Gammon Save Checker Play 32
      gudgen -- Thursday, 29 December 2016, at 11:33 p.m.
      • Gammon Save Checker Play 32
        TraumaBG -- Friday, 30 December 2016, at 1:05 a.m.
        • Gammon Save Checker Play 32
          Timothy Chow -- Friday, 30 December 2016, at 5:08 p.m.
          • Gammon Save Checker Play 32
            TraumaBG -- Friday, 30 December 2016, at 7:26 p.m.
    • Gammon Save Checker Play 32
      neilkaz -- Friday, 30 December 2016, at 5:35 a.m.
  • Gammon Save Checker Play 32
    svilo -- Thursday, 29 December 2016, at 10:22 p.m.
  • Gammon Save Checker Play 32
    svilo -- Thursday, 29 December 2016, at 10:37 p.m.
  • Rollout Result and Brief Commentary
    Paul Weaver -- Friday, 30 December 2016, at 6:25 a.m.