Author: Robert Hyatt
Date: 12:25:37 02/27/06
Go up one level in this thread
On February 27, 2006 at 15:09:43, Tord Romstad wrote: >On February 27, 2006 at 12:23:29, Robert Hyatt wrote: > >>I ran with a flavor of this in CCT8 and noticed no problems whatsoever from a >>tactical perspective. My original thinking when implementing this was that it >>would hurt tactics, but improve positional play, since reducing the depth on the >>oddball moves would tend to drive the tactics over the horizon. Interestingly, >>in testing the idea prior to CCT8, I discovered the opposite. > >That's my experience, too. Tactically, my program is *much* stronger with >late move reductions enabled. Horizon effects are rare. It does happen (but >not very often) that some tactical shot is found one iteration later, but >usually >the time to solution is still shorter. > >I tried a quick run through ECMGCP at 10 seconds/position now. With late >move reductions enabled, my program scored 166/183. When I disabled >them, the score dropped to 150/183. This is a rather significant difference. > >There are also some rather cheap ways to improve the tactical accuracy. >One simple trick which works surprisingly well for me is the following: >If I reduce a move, and at the following node the null move search fails >low, and furthermore the moving piece in the move that refuted the >null move is the same as the moving piece in the reduced depth move, >instantly stop the reduced depth search and re-search with full depth. >Various forms of static threat detection could also help. It is probably >also a good idea not to reduce anything too close to the horizon. > >>So, bottom line, the idea seems workable now. I've got a few other things to >>test, and some are playing with the reduction amount (I used 1.0 plies for CCT8 >>but Mike has been testing with 2.0 so there is room for improvement probably). > >I have never had success with reducing by more than one ply, but of course this >doesn't mean that it is impossible. > >>There are also a few other types of moves that might be excluded, but I am not >>doing this at present (yet). Passed pawn pushes for example probably should be >>excluded, but presently are not. > >I do this, in an indirect way. I evaluate all internal nodes. If a reduced >move >seriously increases the passed pawn eval for the moving side, I cancel the >reduction. I do something similar for king safety, and consider to add other >evaluation components as well. There are plenty of other obvious ideas which >are worth trying here. > >>I'll release all the details once the WCCC event is over, but the idea appears >>to be fully workable despite what "some" will say. :) > >Well, let's rather say that it's fully workable in *some* programs. :-) > >Tord Can you post a link to the ecmgcp positions you are using? I cleaned up my test directory a while back, and on a couple of occasions cleaned up more than I intended. :)
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.