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501 Essential Backgammon Problems #42 -- Rollout + Variants

Posted By: Igor
Date: Wednesday, 28 August 2013, at 4:25 p.m.

In Response To: 501 Essential Backgammon Problems #42 (Igor)

Hitting with 6/4* unstacks the 6pt and fights for initiative; blue can afford to do so due to the blot on the white 5pt. For the three Robertie recommends 13/10 as it unstacks the midpoint, provides another cover for the blot on our 4pt (and let's not forget duplication of 3's and 4's). This is a very natural logical choice. The downside is that blue leaves four blots; not the best idea when you are outboarded. According to the rollouts 16/13 is a viable option. Shorter 5K and 13K rollouts posted previously suggest that 16/13 is better than 13/10, but as I already mentioned, the longer you keep it going, the closer the two plays become.

		White is Player 2 score: 0 pip: 170 Unlimited Game Jacoby pip: 159 score: 0 Blue is Player 1
XGID=-b--a-E-C---dE--Ac-bab--A-:0:0:1:32:0:0:1:0:10
Blue to play 32

1.	Rollout1	16/13 6/4*	eq: -0.102
	Player: Opponent: 47.90% (G:13.35% B:0.87%) 52.10% (G:15.93% B:0.69%) Conf.: ± 0.003 (-0.105...-0.099) - [79.0%] Duration: 5 hours 57 minutes
2.	Rollout1	13/10 6/4*	eq: -0.104 (-0.002)
	Player: Opponent: 47.85% (G:14.83% B:1.17%) 52.15% (G:17.74% B:1.33%) Conf.: ± 0.003 (-0.107...-0.101) - [21.0%] Duration: 5 hours 27 minutes
3.	Rollout2	24/22 16/13	eq: -0.153 (-0.051)
	Player: Opponent: 47.28% (G:11.76% B:0.72%) 52.72% (G:18.31% B:0.55%) Conf.: ± 0.013 (-0.166...-0.140) - [0.0%] Duration: 18 minutes 25 seconds
4.	Rollout2	16/11	eq: -0.156 (-0.054)
	Player: Opponent: 46.57% (G:12.66% B:0.78%) 53.43% (G:16.08% B:0.63%) Conf.: ± 0.011 (-0.168...-0.145) - [0.0%] Duration: 18 minutes 58 seconds
1 46656 Games rolled with Variance Reduction. Dice Seed: 94782038 Moves: 3-ply, cube decisions: XG Roller 2 2592 Games rolled with Variance Reduction. Dice Seed: 94782038 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

13/10 wins more gammons and loses more gammons, so if this is an AtS decision, it could easily be swayed one way or another. Let's bring one more white checker in the zone:

		White is Player 2 score: 0 pip: 163 Unlimited Game Jacoby pip: 159 score: 0 Blue is Player 1
XGID=-b--a-E-C---cE--Ac-cab--A-:0:0:1:32:0:0:1:0:10
Blue to play 32

1.	Rollout1	16/13 6/4*	eq: -0.266
	Player: Opponent: 44.83% (G:11.66% B:0.73%) 55.17% (G:19.09% B:0.84%) Conf.: ± 0.003 (-0.269...-0.263) - [90.6%] Duration: 5 hours 00 minute
2.	Rollout1	13/10 6/4*	eq: -0.269 (-0.003)
	Player: Opponent: 44.72% (G:12.68% B:0.88%) 55.28% (G:21.39% B:1.69%) Conf.: ± 0.003 (-0.272...-0.266) - [9.4%] Duration: 4 hours 34 minutes
3.	Rollout2	16/11	eq: -0.282 (-0.016)
	Player: Opponent: 44.39% (G:10.62% B:0.57%) 55.61% (G:19.53% B:0.67%) Conf.: ± 0.008 (-0.290...-0.274) - [0.0%] Duration: 31 minutes 59 seconds
4.	Rollout3	24/22 16/13	eq: -0.343 (-0.077)
	Player: Opponent: 43.82% (G:9.53% B:0.54%) 56.18% (G:21.71% B:0.61%) Conf.: ± 0.011 (-0.354...-0.332) - [0.0%] Duration: 14 minutes 19 seconds
1 46656 Games rolled with Variance Reduction. Dice Seed: 28412616 Moves: 3-ply, cube decisions: XG Roller 2 5184 Games rolled with Variance Reduction. Dice Seed: 28412616 Moves: 3-ply, cube decisions: XG Roller 3 2592 Games rolled with Variance Reduction. Dice Seed: 92893372 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

The two hitting plays are still virtually tied, but now the safer 16/11 naturally gained in relative equity. Now, one of the reasons to hit loose on our 4pt is to unload the heavy 6pt, so let's change the distribution of spares:

		White is Player 2 score: 0 pip: 170 Unlimited Game Jacoby pip: 161 score: 0 Blue is Player 1
XGID=-b--a-D-D---dE--Ac-bab--A-:0:0:1:32:0:0:1:0:10
Blue to play 32

1.	Rollout1	13/10 6/4*	eq: -0.104
	Player: Opponent: 48.12% (G:14.09% B:1.04%) 51.88% (G:17.90% B:1.35%) Conf.: ± 0.003 (-0.107...-0.101) - [99.5%] Duration: 5 hours 39 minutes
2.	Rollout1	16/11	eq: -0.110 (-0.005)
	Player: Opponent: 47.72% (G:12.34% B:0.73%) 52.28% (G:15.67% B:0.59%) Conf.: ± 0.003 (-0.113...-0.107) - [0.5%] Duration: 5 hours 45 minutes
3.	Rollout2	16/13 6/4*	eq: -0.123 (-0.018)
	Player: Opponent: 47.76% (G:12.63% B:0.81%) 52.24% (G:16.03% B:0.71%) Conf.: ± 0.006 (-0.129...-0.116) - [0.0%] Duration: 1 hour 26 minutes
4.	Rollout3	24/22 16/13	eq: -0.129 (-0.024)
	Player: Opponent: 47.95% (G:11.07% B:0.65%) 52.05% (G:17.42% B:0.54%) Conf.: ± 0.009 (-0.138...-0.120) - [0.0%] Duration: 37 minutes 43 seconds
1 46656 Games rolled with Variance Reduction. Dice Seed: 92893372 Moves: 3-ply, cube decisions: XG Roller 2 10368 Games rolled with Variance Reduction. Dice Seed: 92893372 Moves: 3-ply, cube decisions: XG Roller 3 5184 Games rolled with Variance Reduction. Dice Seed: 92893372 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

Now 16/11 is almost as good as hitting loose for money and might be a better choice AtS depending on given gammon values.

Messages In This Thread

• 501 Essential Backgammon Problems #42
  Igor -- Monday, 26 August 2013, at 1:49 p.m.
  • 501 Essential Backgammon Problems #42
    Adam Torkelson -- Monday, 26 August 2013, at 6:11 p.m.
  • 501 Essential Backgammon Problems #42
    Taper_Mike -- Tuesday, 27 August 2013, at 3:22 a.m.
  • Rollout Result Posted
    Paul Weaver -- Tuesday, 27 August 2013, at 2:29 p.m.
    • Rollout Result Posted
      Igor -- Tuesday, 27 August 2013, at 9:00 p.m.
    • Rollout Result Posted
      neilkaz -- Tuesday, 27 August 2013, at 10:22 p.m.
  • 501 Essential Backgammon Problems #42 -- Rollout + Variants
    Igor -- Wednesday, 28 August 2013, at 4:25 p.m.
    • 51$-31H-41H-63R-42P-32 — Unlimited Games — 2-ply GnuBg Trunc
      Taper_Mike -- Wednesday, 28 August 2013, at 9:55 p.m.
  • 501 #42 ROs
    Stick -- Friday, 30 August 2013, at 8:04 a.m.