Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Unexpected problem with futility pruning ?

Author: Tord Romstad

Date: 15:16:39 12/29/03

Go up one level in this thread


On December 29, 2003 at 16:01:08, Andrew Williams wrote:
>I make sure that I have a legal move available before pruning stuff.

This is good advice, and reminds me of an amusing bug I had in early versions of
Gothmog
(while I was still using normal futility pruning):  In positions which were so
bad that all
moves were pruned because they had no chance of bringing the score anywhere
close,
to alpha, the engine thought:  "I have no moves, but I'm not in check -- It's
stalemate.
Let's return 0".  As a result, the engine would sometimes make horrible
blunders, and
print out PVs where it sacrificed almost all its pieces, with a draw score at
the end of
the line.

Tord



This page took 0.12 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.