Author: David Rasmussen
Date: 11:18:00 01/05/01
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On January 05, 2001 at 08:28:07, Severi Salminen wrote: >>What is the best way to sort moves at the root after each iteration? > >I sort root moves so that PV comes first then other moves sorted by number of >nodes that were visited searching that particular move. > >>What is the best way adjust alpha and beta at the root after each iteration? > >First I do a 1 ply search. Then I do search with 1 pawn wide window. If I fail >high or low I do a research: score-1, INF (fail high) or -INF,score+1 (fail >low). The score is the score returned from the search that failed low or high in >the first place. Notice those +1 and -1. Without those you'll get fail lows and >highs again. I use fail soft and this means that you have to be sure what to >return from search, qsearch and evaluate. A wrong value returned from (say) >futility pruned node means problems. The point is that if you fail high or low >in the first search you have to be sure that the score returned is the other >bound of the true score. > I just reuse the score from the last iteration and center on that with an aspiration windows of one third of a pawn. I do the +1 -1 parts too. At first I found them "ugly", but as far as I can see, it is necesary.
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