Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: How do you insure that Hash Table entries are correct?

Author: Carlos del Cacho

Date: 10:53:16 09/16/00

Go up one level in this thread


On September 16, 2000 at 12:25:27, Larry Griffiths wrote:

>I have tried using a 64-bit hash key and storing it in each hash entry to insure
>that different positions that point to the same hash table entry can be
>verified.
>
>I also have a 32 byte smallboard that I use for debugging.  This smallboard has
>4bits for each piece color and type so I know for sure if the current position
>matches the hash table entry.
>
>The 64-bit hashkey works most of the time, but sometimes different board
>positions produce the same hash-key.
>
>Is there a fail-safe method other than my 32 byte smallboard for insuring that
>different board positions with the same hash keys can be resolved?
>
>Larry.

Since you store also a move from the position (for move ordering), you should
look if it is valid when you retrieve information from the hash table. This
isn't 100% safe but it's ok. I'm currently worried about collisions in null move
searches (no move stored there, so chances of using wrong info increase). What
do you guys do there ?
Carlos



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.