Author: Severi Salminen
Date: 11:57:24 01/05/01
Go up one level in this thread
> There're many possibilities here, and the best one can do is try them all. >What I do in Averno is: > - The first time, I sort with my normal criteria (wining captures, etc...) > - After that, every fail high at the root makes that move become the first of >the list so, after, several fail highs, at the beggining of the list I have the >last fail highs, the most recent first. Could you or have you compared this with the "node" method? Which one gave you the better results? I like the node approach because it gives a priority number for each move in root node "looks" like a sound method. >>>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. > > Aspiration search usually uses the value from the previous search, istead of >this 1 ply search. > My AS window is 25 centipawn. I meant that first I do 1 ply search and the I allways use the score from previous iteration. So the 1 ply search is done with infinite 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. > > I do an intermediate try, adding/substracting 150 centipawns and only if that >fails high/low again, use +INF/-INF. Maybe I should also not give an infinite window at first place but try a wider window first. Well, I try to make my program play so that it improves its position 0.50 pawns on every move so I don't have to re-search ;) >>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 notice I sometimes when I get a fail low at the root, I do a research, and >>>then get a fail high! The most likely explanation is that I am a moron and it >is bug. >> >>Well, we are all morons, so that can't be an explanation. But yes, it must be a >>bug. > > Hashing and null move can very well cause this behaviour, not necessarily a >bug. Ok, I don't do hashing yet. Severi
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.