Author: Gerd Isenberg
Date: 22:29:30 04/27/04
Go up one level in this thread
On April 28, 2004 at 01:11:23, Gerd Isenberg wrote: >On April 27, 2004 at 21:54:49, Uri Blass wrote: > >>On April 27, 2004 at 21:00:22, Vincent Diepeveen wrote: >> >>>On April 27, 2004 at 11:43:36, José Carlos wrote: >>> >>>>On April 27, 2004 at 08:37:34, Tony Werten wrote: >>>> >>>>>On April 27, 2004 at 03:33:26, Bas Hamstra wrote: >>>>> >>>>>>About double nullmove: I tested this in some pawnendgames to see if it could >>>>>>handle zuzwang problems, but I don't see it perform any better than normal >>>>>>nullmove. Can Vincent or you post a position where double null outperforms >>>>>>normal null? I agree the idea is elegant, but I just don't see it work. >>>>> >>>>>I switch it off in pawns only endgames. Couldn't figure out why it wasn't doing >>>>>as well as it sounded. >>>> >>>> I can't think about it now, but I recall this thread where an interesting >>>>discussion about double null move came up: >>>> >>>>http://chessprogramming.org/cccsearch/ccc.php?art_id=241476 >>>> >>>> José C. >>> >>>Christophe wrote that down just to let you guys believe you should search >>>fullwidth. >>> >>>Practical chances of it happening is small, not zero but very close to it. >>>Additionally you can add a single 'if then else' condition in transposition >>>table cutoff to avoid the theoretical scenario that christophe describes. >>> >>>Look the alternative to double nullmove is doing something dead slow like what >>>Gerd is doing, or what i used to do in my draughtsprogram; a verification >>>search, which is just a fullwidth search of n-R ply. So not the later posted in >>>ICGA verification search. Verification search already was excisting in other >>>publications than in the ICGA. So Omid just stole the name kind of for something >>>working crappy :) >> >>No >> >>Omid did not steal the idea. >> >>You simply did not understand Omid's ideas. >>Omid's idea is not mainly to detect zugzwangs but to detect tactics earlier. >> >>Null move pruning means that there are tactics that you need more plies to see >>because of the horizon effect when you cannot detect the threat. >> >>With verified null move pruning you can see it 1 or 2 plies earlier. >> >>Doing checks in the qsearch cannot solve the problem because there is tactics >>that is not based on checks. >> >>> >>>Basically all those approaches eat shitload of nodes to say it *very* polite. >> >>Basically I see no reason that verification search to detect zugzwangs needs to >>eat many nodes(Omid's idea is not verification search) and common sense tells me >>that if the depth is reduced enough it does not eat many nodes. >> >>Uri oups, sorry for the empty reply... I tried double nullmove suggested by Vincent too, without any precondition like eval - margin >= beta. Vincent is probably right - it seems to work great, and solves a lot of test positions a few percent faster. But with some positions, specially with fail-high or -low behaviour the solution needs more than the double time than single nullmove in a row with verification search in my program. Two examples from BT-test: 2bq3k/2p4p/p2p4/7P/1nBPPQP1/r1p5/8/1K1R2R1 b - - ; bm c8e6 k7/8/PP1b2P1/K2Pn2P/4R3/8/6np/8 w - - ;bm e4e1 Cheers, Gerd
This page took 0.02 seconds to execute
Last modified: Thu, 07 Jul 11 08:48:38 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.