Author: Ed Schröder
Date: 14:37:28 01/30/04
Go up one level in this thread
On January 27, 2004 at 07:57:30, Tord Romstad wrote: >On January 27, 2004 at 07:21:53, Ed Schröder wrote: > >>On January 26, 2004 at 11:10:55, Tord Romstad wrote: >> >>>Yes. That is why I don't do this at all nodes, but only when the evaluation >>>function reports that the current position is "sufficiently close to >>>quiescent" that it is safe to rely on the relatively simple SEE. >>> >>>Consider the simplest possible example: >>> >>>Assume that the side to move has no hanging, pinned or overloaded pieces, >>>and that the opponent has an undefended hanging piece. If the static >>>eval plus the value of the hanging piece is considerably bigger than >>>beta, it is reasonably safe to return beta. This works even with >>>a very simple SEE. >> >>Tord, >> >>I am probably doing something similar, to be sure can you demonstrate the above >>with a (diagram) example? > >Sure. The following examples look rather artificial, but I still think >they are good enough to illustrate the idea. Assume that the following >position occurs with white to move in the qsearch, and that beta has >a value close to zero: > >[d] 4k3/2b5/5q2/4P3/8/8/6K1/6Q1 w - - > >Instead of generating and searching any captures, my qsearch just returns >a fail high score immediately in this position. Black's queen is hanging, >capturing it will bring the score considerably above beta, and there are no >"warning signs" for white (i.e. no hanging, pinned or overloaded pieces). > >If we move the white king or queen to h2, white's pawn on e5 is pinned. >This is detected by my evaluation function. In such cases, I generate >and search captures. > >If we move black's bishop to b6, I also generate and search the captures >rather than returning a fail high score immediately, because now white's >queen is also hanging. > >Does this resemble what you are doing? Hi Tord, Thanks for explanation. No I don't do this trick, will try and see what happens. My best, Ed
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.