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Subject: Re: Fritz and Junior clearing of hash tables after every move

Author: Larry Griffiths

Date: 20:01:08 02/12/99

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On February 12, 1999 at 01:57:01, Komputer Korner wrote:

>In Henri Arsenault's Games Domain review of Fritz 5-16 bit he states that "After
>each variation is analyzed, the hash table is emptied, so this is a much more
>efficient way to analyze a game."  I say Oh REALLY ???!!!!!!!!!!
>Any correct hash table info (even a full one) is better than no hash info. When
>the hash table is full, programs implement a replace hash algorithm which
>determines ( many programs have 2 hash tables or even 3 if you count the pawn
>hash table) which hash entries get knocked out. If a hash entry  is not there
>(got knocked out) and that position at the same depth comes up again, then the
>program of course has to calulate the score over again. BUT if it doesn't get
>knocked out then time is saved. That is the whole purpose of a hash table. I
>realize that initializing the hash table takes cpu time, but whether the hash
>table is full or empty at the beginning of the move should not affect this.
>Therefore I wonder why the Fritz and Junior engines do this. Don't they play a
>little weaker because of this practice?
>--
>Komputer Korner

I am still trying to get the hash table to work in my program and am currently
clearing the hash tables after every iteration.  In theory, I agree with
You and Bob Hyatt.  My program seems to make stupid moves when the hash table
is included, but makes exceptionally stupid moves when I do not clear
the hash table.  I am looking for bugs in my hashtable code at this time.


Larry   :o)



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