Author: Bruce Moreland
Date: 16:00:58 07/04/01
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On July 04, 2001 at 18:02:46, Alvaro Jose Povoa Cardoso wrote: >Some time ago I saw here a discussion about adjusting mate scores. >Dr. Hyatt said we should do so only if they were exact scores. >Others have said we could also adjust upper and lower bounds mate scores. >Can some one please elaborate a 'complete' explanation on this? > >In my checkers program if I adjust every (exact, upper or lower) mate score I >can get wrong mate positions from hash. >For example: I can get a position that says white wins in 50 moves (!!!) but in >reality it loses in 3 moves. > >On the other hand if I adjust only exact scores those errors disappear, but >another one comes in. >I get mate in 15, then mate in 14, then mate in 13, then mate in 15 again, then >mate in 14, then mate in 13... >I wonder how my program can make progress towards a win with these scores. > >Are these errors correlated? > > >As an example here is the output of a (portuguese) checkers game in wich I >adjust only exact scores: > >White: 20 ply Black: 20 ply IDS_Step = 2 > > Nº Move Score Nodes > > 1W 8-19 31978 39,680,403 > 2B 3x13 31979 11,938,167 > 3W 19-14 31980 7,539,580 > 4B 18x11 31981 88,312 > 5W 9x18 31982 20 > 6B 25x14 31983 18 > 7W 5-10 31984 90,491 > 8B 14x5 31985 16 > 9W 1x14x4 31986 113 > 10B 17-13 31987 60,257 > 11W 4-14 31988 1,281 > 12B 13-9 31989 1,485 > 13W 14-32 31990 514 > 14B 31-27 31991 300 > 15W 32-14 31992 84 > 16B 27-22 31993 84 > 17W 14-1 31994 130 > 18B 22-18 31995 59 > 19W 1-32 31996 78 > 20B 9-5 31995 238 > 21W 32x1 31996 55 > 22B 18-13 31997 6 > 23W 1-14 31998 24 > 24B 13-9 31997 54 > 25W 14-19 31998 32 > 26B 9-5 31999 2 > 27W 19x1 32000 2 > > Totals -> 59,401,805 > > >If I adjust every mate score the progress towards a win is perfect, but as I >said before I can get wrong mate positions from hash. >Can someone please help with an explanation (as complete as possible) on the >matter of adjusting mate scores? > >Thank you all, >Alvaro Cardoso Solve this problem for once and for all by only storing mate scores as bounds. You don't have to cut off on mates. bruce
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