Author: Robert Hyatt
Date: 09:56:43 03/08/98
Go up one level in this thread
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...
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