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Rollout: How would you categorize this position?

Posted By: Timothy Chow
Date: Sunday, 28 February 2010, at 8:47 p.m.

In Response To: How would you categorize this position? (Timothy Chow)

What makes this position tricky, in my opinion, is that it can develop in several different ways, and so one has to be alert to all the different possibilities and shift gears should the dice swing the game suddenly in a new direction. White is stacked (those ugly checkers on the 3-point are a telltale sign of unwelcome double-5's) and there are some awkward sequences that allow Blue to send another checker back. This suggests that Blue is actually the favorite and that Blue should just sit on his ace-point anchor and wait for White's position to deteriorate. On the other hand if White's back checker escapes then suddenly Blue is in danger of being stuck in a desperate ace-point game.

These considerations might seem to suggest controlling the outfield with 13/11 13/10 or building a prime with 13/10 6/4 or 13/8 (the last of these was my play OTB). However, this turns out to be a situation where simply building the home board with 7/4 6/4 is strongest. Almost no matter how the game goes, the four-point will be a strong asset. And if White hits the blot then Blue is not upset at having another checker back to maximize contact. The point is that if White escapes to the outfield next roll and Blue misses, Blue is often better off with a third checker back and the four-point already made than with just the ace-point anchor and a three-point board.

gnubg	115
tchow	136
Position ID: PJ7LACDGboMBMA Match ID: cAkNACAAAAAA

#		Ply	Move	Equity
•	1	R	7/4 6/4	+0.310
			0.590 0.151 0.005 - 0.410 0.118 0.009 +0.208 +0.310 0.001 0.002 0.000 - 0.001 0.001 0.000 0.004 0.011
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]
	2	R	13/11 13/10	+0.241 ( -0.069)
			0.563 0.138 0.006 - 0.437 0.116 0.007 +0.146 +0.241 0.001 0.002 0.001 - 0.001 0.002 0.000 0.004 0.009
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]
	3	R	13/10 6/4	+0.227 ( -0.083)
			0.571 0.147 0.006 - 0.429 0.151 0.015 +0.129 +0.227 0.002 0.002 0.000 - 0.002 0.001 0.001 0.004 0.011
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]
	4	R	6/1*	+0.217 ( -0.093)
			0.548 0.186 0.006 - 0.452 0.131 0.010 +0.147 +0.217 0.001 0.002 0.000 - 0.001 0.002 0.001 0.004 0.011
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]
	5	R	24/21 13/11	+0.184 ( -0.127)
			0.560 0.140 0.007 - 0.440 0.168 0.009 +0.089 +0.184 0.001 0.002 0.000 - 0.001 0.002 0.001 0.003 0.010
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]
	6	R	13/8	+0.147 ( -0.163)
			0.542 0.130 0.005 - 0.458 0.115 0.006 +0.098 +0.147 0.001 0.002 0.000 - 0.001 0.001 0.000 0.003 0.009
			Full cubeful rollout with var.redn.
			1296 games, Mersenne Twister dice gen. with seed 849955795 and quasi-random dice
			Play: supremo 2-ply cubeful prune [world class]
			keep the first 0 0-ply moves and up to 16 more moves within equity 0.32
			Skip pruning for 1-ply moves.
			Cube: 2-ply cubeful prune [world class]

Messages In This Thread

• How would you categorize this position?
  Timothy Chow -- Saturday, 27 February 2010, at 1:42 a.m.
  • How would you categorize this position?
    Marv Porten -- Saturday, 27 February 2010, at 4:06 a.m.
  • How would you categorize this position?
    Peter G. -- Saturday, 27 February 2010, at 9:21 a.m.
    • How would you categorize this position?
      svilo -- Saturday, 27 February 2010, at 1:37 p.m.
  • How would you categorize this position?
    Martin -- Saturday, 27 February 2010, at 12:46 p.m.
    • How would you categorize this position?
      John O'Hagan -- Saturday, 27 February 2010, at 1:44 p.m.
      • How would you categorize this position?
        Martin -- Saturday, 27 February 2010, at 4:45 p.m.
  • How would you categorize this position?
    Chuck Bower -- Saturday, 27 February 2010, at 3:23 p.m.
  • How would you categorize this position?
    christian munk-christensen -- Saturday, 27 February 2010, at 3:44 p.m.
  • Rollout: How would you categorize this position?
    Timothy Chow -- Sunday, 28 February 2010, at 8:47 p.m.