Author: James Robertson
Date: 21:24:38 05/13/99
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On May 13, 1999 at 23:12:41, Dan Homan wrote: > >I've tried the mtdf algorithm a few times with no luck. It was >always noticably slower than pure PVS. (For reference: mtdf is >an algorithm which uses a series of null-window searches from the >root to narrow in and find the true score of a position.) > >Today I tried mtdf again, but this time with more determination. >It is an easy change to my program because all I need to modify >is the loop that calls my PVS function from the root. Again, I found >that it was much slower than normal PVS at first. However, >by modifying the algorithm to use an adaptive step-size (meaning that >I don't try neighboring (+/- 1 point) windows for re-searches but >rather try to bound the score more efficently) and by >reducing my score resolution from 1/100 th of a pawn to 1/25 th of >a pawn, I got better results from mtdf than from pure PVS. > >I went from 277 correct solution on the WAC test set (5 sec limit on a >Cel 400) to 281 correct solutions with mtdf. My rms solution time for >both runs (with and without mtdf) were nearly the same. Of course, >these tests are not really conclusive... For example I don't know how >pure PVS will do with 1/25 th of a pawn scoring rather than 1/100 th. >What this does indicate to me is that mtdf is a viable solution. Previously, >I had assumed it would be very difficult to implement effectively. > >If I decide to commit to mtdf, there are (presumably) more optimizations >I could take advantage of. What kind of experience do other programmers >have with mtdf? > > - Dan Where can I find out more about mtdf? James
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