Author: Tord Romstad
Date: 08:06:34 07/22/04
Go up one level in this thread
On July 22, 2004 at 09:57:37, martin fierz wrote: >probcut will work on the majority of positions where one side has bludered >material. to get it working for the cases where one side sacced material for a >deadly attack is going to be the problem! I don't use probcut, but I sometimes reduce the search depth in positions when it seems clear that one side is winning (particulary in the endgame, where the null move tends to be less effective than in earlier phases of the game). The problem you describe above is not impossible to cope with, at least if you evaluate internal nodes. The idea is to look at the material *and* the positional evaluation of the position, and perhaps to subdivide the positional evaluation into its various components. If one side is clearly ahead in material, and at the same time has an advantage in most positional factors, it is usually safe to reduce the search depth or (in extreme cases) prune the entire subtree. In simple endgames, this can often be done almost without any risk. It is more difficult in the middle game, but it is still possible to make it work. A related trick which I consider interesting is what I call "compensation extensions". These are used when one side is clearly ahead in material, but the other side has a huge positional advantage (usually in the form of a dangerous attack or advanced passed pawns). In such positions, the static eval tends to be highly unreliable. It makes sense to extend the search in an attempt to find out what happens when the dust settles. Tord
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.