Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Razoring?

Author: Peter Fendrich

Date: 12:02:10 01/26/99

Go up one level in this thread


On January 26, 1999 at 11:56:50, Steve Maughan wrote:

>I've heard of this technique but am not sure exactly what it is.  Could someone
>please explain it?
>
>Regards
>
>Steve Maughan

Like the term "selective program" I don't think there is only one definition.
The first time I heard about razoring in chess programs was in the article:
"Tree-Searching and Tree-Pruning Techniques" by John Birmingham and Peter Kent
at 1977. It was in "Advances in Computer Chess 1" wich I don't have but I got
the article from some other book.
They described razoring like this:
1) In a node make and search the first n (few) moves.
2) The rest of the moves are first evaluated by the static evaluator. If the
evaluator didn't reach alpha they just skipped the move instead of of searching
it.

At that time it probably was a good idea when the programs reached a few plies.
This old style of razoring is better done by Null moves today, IMHO...

A more modern approach can be found at Dark Thought's site, especially at the
page: http://wwwipd.ira.uka.de/Tichy/DarkThought/node29.html
They just shortens the depth if the razoring condition is true.

//Peter



This page took 0.01 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.