Author: Robert Hyatt
Date: 13:15:25 09/06/02
Go up one level in this thread
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.
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