Author: Vincent Diepeveen
Date: 11:18:59 04/07/04
Go up one level in this thread
On April 07, 2004 at 04:32:48, Uri Blass wrote: >On April 07, 2004 at 04:06:38, Tord Romstad wrote: > >>The following idea is still untested, but unless I am missing something it >>is guaranteed to reduce the number of nodes without any risk. The idea is >>fairly obvious, and I am sure some of you are already using it, but I still >>don't think it is widely known. >> >>At a node where the remaining depth is sufficiently big that a null move >>would not drop us directly into the qsearch, and beta > DRAW_SCORE, avoid >>doing a null move search if the move leading to the node was a reversible >>move. The point is that we know that the null move search is a waste of >>time in this case. After the null move, the opponent can just reverse >>his move, with a repetition draw score. >> >>Tord > >Even if the idea was correct then I think that it is private case of ETC >but maybe I do not understand ETC. > >A possible idea is to detect the pattern >from1 to1 from2 to2 to1 from1 in the last 3 moves and to try to2 from2 first in >case that it is legal because it gives draw score even without search. > >it can be also in case of null moves(null move is a1a1) > >If you detect a1a1 b1c3 a1a1 then the first move to search is c3b1. > >Note that in that case it is important not to save the move in the hash tables >or in the killer moves and I think that even changing the history is bad. > >I did not try it in movei but I may do it. >I remember that Junior used that idea too much and there was a case when it >showed a wrong draw score based on 3 moves because it even did not care to check >if the 4th move that cause a repetition is legal and it was illegal. > >Uri All not needed what you write down here. What a bunch of nonsense. Just treat the nullmove like a pawn move and restart counting in the transposition array the same position count. then you get more cutoffs even because you want a fail low for the c3b1 move, not a fail high. A fail low gives a nullmove cutoff and saves you out searching a huge tree.
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.