Author: Komputer Korner
Date: 21:28:11 03/11/98
Go up one level in this thread
On March 08, 1998 at 12:56:43, Robert Hyatt wrote: >On March 08, 1998 at 11:53:27, Aaron wrote: > >> >>On March 06, 1998 at 22:51:02, Robert Hyatt wrote: >> >>>On March 06, 1998 at 20:41:44, Stuart Cracraft wrote: >>> >>>>For a long time, my program had been sparring with >>>>another program. The result over 50 games was about >>>>40 losses and 10 draws. Never a win. >>>> >>>>I suspected a misbalance of positional factors which >>>>resulted in >1 pawn positional contribution to the >>>>evaluation score as well as poor development and >>>>poor analysis of backward pawns. >>>> >>>>It seemed likely that by improving the development and >>>>backward pawn factors and minimizing the positional >>>>contributions swaying the material score, this might >>>>help. >>>> >>>>So I converted to millipawns (a 5 second change for >>>>me and a 10 minute compile). Also I added David Levy's >>>>development terms from "The Joy of Computer Chess" >>>>and added analysis of backward pawns. >>>> >>>>Then I played it against its sparring partner and it >>>>immediately won its first game. There were no outright >>>>technical blunders and it kept the game together. >>>> >>>>I think another good approach is to analyze your >>>>worst/largest positional contribution to the overall score >>>>and find out what kinds of positions are producing these >>>>big swings in the score that are not materially based and >>>>start lessening the heuristic scores to bring the positional >>>>score back within a narrow window. >>>> >>>>For example, a king scoring function that results in massive >>>>changes in the positional score could be a blunder-creator >>>>not a king-saver! By going to millipawns first it's possible >>>>to see a formerly blundering program actually play half-decently >>>>while still working the behind-the-scenes bugs. Later, centipawns >>>>could be restored, if desired, so that positional sacrifices might >>>>be made on a more conservative basis. >>>> >>>>I am curious regarding the other program's authors on this bulletin >>>>board, what are the largest positional heuristics you award or >>>>penalize positions for? And do you use centipawn or millipawn >>>>and why? And have you experimented with the other and why not? >>>> >>>>--Stuart >>> >>> >>>I started with centipawns, switched to millipawns, then back to >>>centipawns >>>again. I don't believe that *I* can accurately divide a positional >>>score >>>into fractions of 1/1000th... I don't even believe I can divide it into >>>pieces of 1/100th... >>> >>>I also have significant scores... many are worth a pawn, several are >>>worth way more... ie king safety can be up to +/- 3 pawns or so de- >>>pending on how exposed and how many pieces are left for the opponent. >>>Ditto for some endgame things like connected passers on the 6th/7th, or >>>passer advanced with king support, and so forth. >>> >>>Only way I know to tune is play and watch and, if you are a good enough >>>player, try to figure out where your program went wrong and adjust the >>>weights to stop that... >> >>Hmm. is there any program out there that allows a non-programmer to do >>stuff like that? > >I believe Nimzo does. Others give you access to a small subset of the >evaluation's positional parameters... Nimzo 3 and 3.5 not Nimzo 98. -- Komputer Korner
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