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41$-51S-55, 62$-51S-55 and 51$-51S-55

Posted By: Nack Ballard
Date: Saturday, 19 January 2019, at 11:53 p.m.

In Response To: 21$-51S-55 (David Rockwell)

		White is Player 2 score: 0 pip: 161 Unlimited Game Jacoby Beaver pip: 164 score: 0 Blue is Player 1
XGID=-aa--AD-C--AdD---d-e----B-:0:0:1:55:0:0:3:0:10
21$-51S-55 -- best is P

eXtreme Gammon Version: 2.10

Three related positions, shown below, come to mind. (They are side by side by side, if your font is not too large and your window is sufficiently wide.) In each case, the only change is that Blue's 11pt checker is on a different point.

(1) 41$-51S-55 (floating checker is on Blue's 9pt) shows to be consistent with David's comment in regards to the featured 21$-51S-55 position ("Don't strip the six point. Just make the three - 55P"). The P-over-A margin is closer when Blue's blot is on his 9pt (as you will see after comparing John's rollout) because P leaves more shots and A gains 54K/P duplication.

[A contrasting variant position is 41$-21S-55 (White's 8pt checker on her 11pt), where A beats P by .017 (5k rollout not shown). White's extra blot/builder motivates Blue to Attack. So, though a key factor, more than just the number of checkers on the 6pt needs to be taken into account.]

(2) 62$-51S-55 (though unlikely to arise today) is also consistent with David's comment. Blue should change his play to A (Attack, 8/3(2) 6/1*(2)) because his 6pt will no longer become stripped.

(3) 51$-51S-55: The floating checker is on Blue's 8pt. Here, A (Attack, 8/3(2) 6/1*(2)) is correct despite stripping the 6pt. There is more than enough compensation in that A doesn't also blot the 8pt.

		White is Player 2 score: 0 pip: 161 Unlimited Game Jacoby Beaver pip: 162 score: 0 Blue is Player 1
XGID=-aa--AD-CA--dD---d-e----B-:0:0:1:55:0:0:3:0:10
41$-51S-55 -- best is P

1.	Rollout1	13/3(2)	eq: +0.058
	Player: Opponent: 50.70% (G:17.84% B:0.73%) 49.30% (G:14.13% B:1.02%) Conf.: ± 0.008 (+0.050...+0.066) - [100.0%] Duration: 39 minutes 22 seconds
2.	Rollout1	8/3(2) 6/1*(2)	eq: +0.035 (-0.023)
	Player: Opponent: 48.96% (G:20.35% B:0.45%) 51.04% (G:15.29% B:1.07%) Conf.: ± 0.009 (+0.026...+0.044) - [0.0%] Duration: 35 minutes 37 seconds
3.	Rollout2	13/3 8/3 6/1*	eq: -0.018 (-0.076)
	Player: Opponent: 48.87% (G:17.62% B:0.55%) 51.13% (G:15.37% B:1.06%) Conf.: ± 0.018 (-0.036...+0.000) - [0.0%] Duration: 5 minutes 10 seconds
1 5184 Games rolled with Variance Reduction. Dice Seed: 26935557 Moves: 3-ply, cube decisions: XG Roller 2 1296 Games rolled with Variance Reduction. Dice Seed: 26935557 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

		White is Player 2 score: 0 pip: 161 Unlimited Game Jacoby Beaver pip: 159 score: 0 Blue is Player 1
XGID=-aa--AE-C---dD---d-e----B-:0:0:1:55:0:0:3:0:10
62$-51S-55 -- best is A

1.	Rollout1	8/3(2) 6/1*(2)	eq: +0.158
	Player: Opponent: 51.21% (G:21.93% B:0.46%) 48.79% (G:13.65% B:0.86%) Conf.: ± 0.007 (+0.151...+0.165) - [100.0%] Duration: 14 minutes 51 seconds
2.	Rollout1	13/3(2)	eq: +0.113 (-0.045)
	Player: Opponent: 51.65% (G:18.35% B:0.64%) 48.35% (G:12.55% B:0.73%) Conf.: ± 0.008 (+0.105...+0.120) - [0.0%] Duration: 19 minutes 26 seconds
1 5184 Games rolled with Variance Reduction. Dice Seed: 21050423 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

		White is Player 2 score: 0 pip: 161 Unlimited Game Jacoby Beaver pip: 161 score: 0 Blue is Player 1
XGID=-aa--AD-D---dD---d-e----B-:0:0:1:55:0:0:3:0:10
51$-51S-55 -- best is A

1.	Rollout1	8/3(2) 6/1*(2)	eq: +0.208
	Player: Opponent: 52.61% (G:21.26% B:0.49%) 47.39% (G:12.39% B:0.68%) Conf.: ± 0.017 (+0.192...+0.225) - [100.0%] Duration: 4 minutes 35 seconds
2.	Rollout1	13/3(2)	eq: +0.097 (-0.111)
	Player: Opponent: 51.55% (G:17.37% B:0.62%) 48.45% (G:12.50% B:0.68%) Conf.: ± 0.015 (+0.082...+0.112) - [0.0%] Duration: 5 minutes 13 seconds
1 1296 Games rolled with Variance Reduction. Dice Seed: 26935557 Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.10

In summary (assuming White's floating checker is stacked, not blotted): If Blue's floating checker is blotted (on the 11pt or 9pt), play P. If it is stacked (on the 6pt or 8pt), play A.

Nack

Messages In This Thread

• 21$-51S-55
  John O'Hagan -- Friday, 18 January 2019, at 8:35 p.m.
  • 21$-51S-55
    MishyPoo -- Friday, 18 January 2019, at 11:24 p.m.
  • 21$-51S-55
    David Rockwell -- Saturday, 19 January 2019, at 2:10 a.m.
    • 21$-51S-55
      neilkaz -- Saturday, 19 January 2019, at 4:52 p.m.
    • 41$-51S-55, 62$-51S-55 and 51$-51S-55
      Nack Ballard -- Saturday, 19 January 2019, at 11:53 p.m.
      • 41$-51S-55, 62$-51S-55 and 51$-51S-55
        David Rockwell -- Monday, 21 January 2019, at 5:36 p.m.
  • 21$-21S-55 (slightly different)
    Nack Ballard -- Saturday, 19 January 2019, at 5:28 p.m.
    • Table of Eight Positions (x1$-x1S-55)
      Nack Ballard -- Sunday, 20 January 2019, at 1:31 a.m.
    • 21$-21S-55 (two overriding plays)
      Nack Ballard -- Tuesday, 22 January 2019, at 12:06 a.m.
      • 21$-21S-55 (two overriding plays)
        Nack Ballard -- Sunday, 27 January 2019, at 4:02 a.m.
  • 21$-51S-55
    John O'Hagan -- Saturday, 19 January 2019, at 11:41 p.m.
    • RO in above post *NM*
      John O'Hagan -- Saturday, 19 January 2019, at 11:42 p.m.
    • 21$-51S-55
      Colin Owen -- Sunday, 20 January 2019, at 3:54 p.m.
      • 21$-51S-55
        John O'Hagan -- Monday, 21 January 2019, at 1:31 a.m.
        • 21$-51S-55
          Colin Owen -- Monday, 21 January 2019, at 3:27 a.m.
          • 21$-51S-55
            John O'Hagan -- Monday, 21 January 2019, at 3:30 a.m.