Because Gnugb plays based on the score and cube value (When in Match play). When it evaluates it doesn¹t blindly use the 2 sided bearoff database because the static values the 2 sided database don¹t account for score by itself. Jankowski¹s forumlas are applied to the values that come from the DB and the eval continues. The bigger question is, is Jankowski¹s formula at fault in how we use it.
I don¹t see this as a bug still. But it doesn¹t mean the methodology has been verified. On 04/09/09 10:56 PM, "Neil Robins" <[email protected]> wrote: > It has occurred to me that in a position like this previously discussed one: > > http://www.bgonline.org/forums/webbbs_config.pl?noframes;read=47213 > > GNU Backgammon Position ID: gwEAQCoAAAAAAA > Match ID : cAmgACAAGAAA > +13-14-15-16-17-18------19-20-21-22-23-24-+ O: gnubg > | | | O O | OOO 2 points > | | | O O | OO > | | | | OO > | | | | OO > | | | | OO > v| |BAR| | 5 point match (Cube: 1) > | | | | XX > | | | | XX > | | | | XX > | | | | XX On roll > | | | X X X X | XXX 3 points > +12-11-10--9--8--7-------6--5--4--3--2--1-+ X: Neil > > The MWC chance following Double/Take is directly obtainable from the Two-Sided > Database. Doubling produces an automatic redouble so the situation is in > effect cubeless. > The DB gives Cubeless equity: +0.4707. > > Therefore where x = MWC/100 > x - (1 - x) = 0.4707 > x = 0.73535 > MWC = 73.535% after Double/Take > This is in very close agreement with the XG rollout. > > Is there any reason GNU analysis cannot use this exact method? > > I feel I still get complete nonsense here with the latest windows build. > > 7-ply cubeless MWC 67.39% (Money: +0.387) > 0.694 0.000 0.000 - 0.306 0.000 0.000 > Cubeful equities: > 1. No double 70.06% > 2. Double, pass 75.08% ( 5.01%) > 3. Double, take 69.36% ( -0.70%) > Proper cube action: No double, take (12.3%) > > It also sure worries me to get rollout results that are quite certainly wrong. > > Rollout details: > Centered 1-cube: > 0.728 0.000 0.000 - 0.272 0.000 0.000 CL 68.25% CF 70.66% > [0.000 0.000 0.000 - 0.000 0.000 0.000 CL 0.00% CF 0.00%] > Player gnubg owns 2-cube: > 0.732 0.000 0.000 - 0.268 0.000 0.000 CL 81.71% CF 73.16% > [0.000 0.000 0.000 - 0.000 0.000 0.000 CL 0.00% CF 0.00%] > Full cubeful rollout with var.redn. > 129600 games, Mersenne Twister dice gen. with seed 865036646 and quasi-random > dice > Play: 2-ply cubeful prune [world class] > keep the first 0 0-ply moves and up to 8 more moves within equity 0.12 > Skip pruning for 1-ply moves. > Cube: 2-ply cubeful prune [world class] > > > _______________________________________________ > Bug-gnubg mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/bug-gnubg
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