On Tue, Jun 24, 2008 at 11:32 AM, Achim Mueller <[EMAIL PROTECTED]> wrote:
The point is not a technical bug but the fact that gnubg totally > misevaluates a position at 0ply that actually should be handled easily. > I put some more positions at http://www.acepoint.de/index.php?id=37. This > section will be extended from time to time. > Another idea is to open a section at www.gnubg.org that can be filled by > readers and users also. > > Actually this one is not so easy I think. A quick 0/2-ply rollout suggests that this is a heavily cube-influenced checker play: 1. Rollout 21/15 8/4 Eq.: +0,431 61,3% 7,5% 0,4% - 38,7% 3,4% 0,1% CL +0,283 CF +0,431 [ 0,1% 0,1% 0,1% - 0,1% 0,1% 0,0% CL 0,003 CF 0,007] Full cubeful rollout with var.redn. 1296 games, Mersenne Twister dice gen. with seed 826408977 and quasi-random dice Play: 0-ply cubeful prune [expert] Cube: 2-ply cubeful prune [world class] 2. Rollout 21/11 Eq.: +0,393 ( -0,037) 60,6% 5,7% 0,4% - 39,4% 4,8% 0,1% CL +0,230 CF +0,393 [ 0,1% 0,1% 0,1% - 0,1% 0,1% 0,0% CL 0,003 CF 0,008] Full cubeful rollout with var.redn. 1296 games, Mersenne Twister dice gen. with seed 826408977 and quasi-random dice Play: 0-ply cubeful prune [expert] Cube: 2-ply cubeful prune [world class] 3. Rollout 21/17*/11 Eq.: +0,365 ( -0,066) 64,1% 11,7% 0,4% - 35,9% 12,2% 0,2% CL +0,293 CF +0,365 [ 0,1% 0,1% 0,0% - 0,1% 0,1% 0,0% CL 0,003 CF 0,007] Full cubeful rollout with var.redn. 1296 games, Mersenne Twister dice gen. with seed 826408977 and quasi-random dice Play: 0-ply cubeful prune [expert] Cube: 2-ply cubeful prune [world class] As you can see, the #3 play, gnubg 0-ply's favourite, still has the highest cubeless equity. It's not surprising that without a lookahead, gnubg fails to see the future cube implications here. I guess what's going on, is that a hit leads to overkill after a dance and subsequent cube. So, cubeful, you don't reap full benefits of this play when it works. The alternative play 21/15 8/4 is less volatile and supposedly leads to more efficient cube usage (after a miss). Greetings, -- Robert-Jan Veldhuizen
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