Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: hash messed up

Author: Dave Gomboc

Date: 16:53:08 10/10/99

Go up one level in this thread


On October 10, 1999 at 15:45:33, Dan Newman wrote:

>On October 09, 1999 at 02:02:44, Scott Gasch wrote:
>
>>I hate to follow my own posting but I solved this problem and wanted to share
>>the solution in case it helps anyone else.
>>
>>First of all, I was counting a hit as a signature match in the hash AND a usable
>>node (depth was enough to be useful).  Some others count any signature match as
>>a hit.  This difference was part of the problem.
>>
>>When I started counting the same way as others I noticed my hash rate was 49.97%
>>on Fine 70 (see previous post).  This lead me to suspect something was wrong
>>with side to move which turned out to be true.  Black to move positions were
>>overwriting white to move same positions and vice versa.
>>
>
>I prevent this by having separate hash tables for black and white.  This
>also effectively increases the hash code by one bit--to 65 bits.  (Not
>that it's really needed...)  The other way is to (of course) hash in a
>side to move bit pattern--but that has always seemed chancy to me somehow.

Okay, but does this seem "chancier" than any other part of the hashing process?
:-)

>-Dan.

Dave



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.