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Rollouts and After-Thoughts

Posted By: Daniel Murphy
Date: Sunday, 16 December 2012, at 10:56 p.m.

In Response To: Rollouts and After-Thoughts (rambiz)

If it is true, that at DMP the opponent shouldn't hit, why don't we force him to hit by playing 13-11 6-1, in DMP position!?

While 13/6 forces White to hit with no rolls, playing 13/11 6/1 forces White to hit only with 64 42 22 and 44. Everything else White can play by advancing the prime (66 or 33), or by advancing 1 or 2 back checkers without hitting.

So: six rolls that force a hit, which gives Blue a chance to anchor. Is that good for Blue? Your DMP rollout suggests "no," and I believe the reason is that with 64 42 or 22 White will hit both outfield blots. The third checker back, I believe, largely negates whatever Blue might gain from anchoring with only two checkers back. With 44 White will play 18/14*/10/6/2*, greatly reducing the chance that Blue will anchor.

In any case, your DMP rollout says that 13/11 6/2 does not do better than 6/1 5/3, despite forcing White to hit with a few rolls. Why is 13/6 a little worse? Well, there are some very improbable sequences, like White rolling 66 followed by 33, but I think the more important reason is that it gives up a very tiny chance, if White's next roll is 51, of either hitting and containing one or more -- probably two -- White checkers, or recirculating the ace point blot to make an anchor. For example, 51 followed by 51 (one of several numbers that hit two checkers), increases Blue's winning chances by quite a lot:

DMP. Blue to play 51

White	114
Blue	93
Position ID: bNsGoQDttgEDEA Match ID: cIkmAAAAAAAE

#		Ply	Move	Equity
•	1	R	13/8*/7*	-0.761
			0.120 0.030 0.002 - 0.880 0.243 0.032 -0.761 -0.761 0.003 0.003 0.001 - 0.003 0.012 0.005 0.005 0.005
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Messages In This Thread

• defending against the free roll
  rambiz -- Thursday, 13 December 2012, at 3:14 a.m.
  • defending against the free roll
    Bob Koca -- Thursday, 13 December 2012, at 6:49 p.m.
    • Rollouts and After-Thoughts
      rambiz -- Saturday, 15 December 2012, at 4:33 p.m.
      • Rollouts and After-Thoughts
        Timothy Chow -- Saturday, 15 December 2012, at 11:05 p.m.
        • Rollouts and After-Thoughts
          rambiz -- Sunday, 16 December 2012, at 4:09 a.m.
          • Rollouts and After-Thoughts
            Bob Koca -- Sunday, 16 December 2012, at 6:49 p.m.
          • Rollouts and After-Thoughts
            Daniel Murphy -- Sunday, 16 December 2012, at 10:56 p.m.
            • Rollouts and After-Thoughts
              rambiz -- Monday, 17 December 2012, at 9:36 p.m.
              • Stick, Delete my Post above please
                rambiz -- Monday, 17 December 2012, at 9:42 p.m.
            • Rollouts and After-Thoughts
              Daniel Murphy -- Monday, 17 December 2012, at 11:49 p.m.