Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: About debugging HashTables implementation .

Author: Pat King

Date: 12:28:26 04/10/02

Go up one level in this thread


On April 09, 2002 at 12:11:08, Andrew Williams wrote:

>On April 09, 2002 at 11:56:45, Pat King wrote:
>
>>On April 08, 2002 at 15:17:46, Robert Hyatt wrote:
>>
>>>How do you define "collision"?  Normally this means two different board
>>>positions produce the same hash signature.  If you are getting _those_ you
>>>have a Zobrist hashing bug.
>>
>>How do you detect collisions, then? Record the entire position in the hash
>>table? Even for a debug build, that seems like it would be impractical. >>Although undetected hash bugs are even less practical :)
>>
>
>You check to see if the move stored in the hash entry is legal or not. If
>the hash keys match but the move isn't legal in the position, it means that
>you have a hash collision.
>
>Andrew

But you rely on the hashed positions being different enough for that move to be
illegal. Certainly, your technique detects collisions, but not all collisions!?

Pat



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.