Author: Tony Werten
Date: 13:26:44 09/06/02
Go up one level in this thread
On September 06, 2002 at 16:15:25, Robert Hyatt wrote: >On September 06, 2002 at 16:06:43, Tony Werten wrote: > >>On September 06, 2002 at 16:03:06, Robert Hyatt wrote: >> >>>On September 06, 2002 at 15:46:53, Tony Werten wrote: >>> >>>>On September 06, 2002 at 14:45:11, Dann Corbit wrote: >>>> >>>>>Did anyone notice his cutoff idea in the evaluation function? >>>>> >>>>>It seems to me to be a very good idea, and I don't know if others have tried it >>>>>out. >>>>> >>>>>Basically, it consists of three modes with two early exits... >>>>> >>>>>1. If the material + structure score alone is dominant enough, it exits right >>>>>away. >>>>>2. Otherwise, it processes the piece list. If that score is dominant, it exits. >>>>>3. Otherwise, it does a full board control scan for all 64 squares. >>>>> >>>>>It is described starting on page 62 under the section "3.3.2 Multi Staged >>>>>Design" >>>>>He gets roughly 71% evals returning in stage #1, 13% in stage #2 and 7% in stage >>>>>#3. >>>>> >>>>>It seems like it might be a big win to do it that way. >>>> >>>>It's called lazy eval and is not a good idea. The times it is wrong happen to be >>>>the important ones. >>>> >>>>Tony >>> >>> >>>Two things... >>> >>>First, you _can_ do a lazy eval with zero error. I did it in Cray Blitz and >>>I explained the idea here before... >>> >>>You can compute the possible "positional error" (the amount the score will >>>change max and min) for each type of piece. When you do a lazy eval, you >>>can use this min/max and sum 'em up (or do it incrementally as we did, which >>>can be a headache) so that you know the "independent piece max/min scores". >>> >>>If you lazy eval based on that, you get _zero_ errors because you will _really_ >>>know that the individual piece scores can't produce a number larger than X or >>>smaller than Y, so you can make an informed decision. >>> >>>I don't do that today because each time you change the eval, you have to >>>update those min/max values which is something I would continually forget. >> >>Yes, correct. But when you get 71% hitrate your bounds are not very wide. >> >>> >>>2. You can get good results with remembering the min/max positional scores >>>during a real game. yes, the scores will continue to "widen" and reduce lazy >>>eval exits, but the error rate is not that bad. Compared to the cost. >> >>In XiniX the hitrate drops to <5% quite fast this way. IMO not really worth it. >> >>Tony > > >I don't see it drop that far, but I don't watch it carefully unless I am >suspecting trouble either... I will take a longer look. Might be better for other programs i think. My kingsafety is calculated during the piece evaluations as is my passed pawn score. ( to name 2 big ones ) Tony
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