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Subject: Re: and another Hash Table question...

Author: Daniel Karlsson

Date: 16:59:24 06/03/99

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On June 03, 1999 at 11:37:00, Inmann Werner wrote:

>Hello
>
>the "hit ratio" of hash tables confuses me a bit. What is a hit?
>

I count a hit when the keys match and there is sufficient depth in the table.
Don't care if the score is usable or not.

>I tried the LCTCMB01 position and got
>
>1) 1.520.234 nodes
>2)   263.041 entries in Hash table used
>3) 1.458.957 probes in Hash table
>4)   137.961 entries found
>5)    40.777 entries have a "allright" depth to use
>6)    37.517 match alpha, beta (upper and lower fails) and are used!
>
>so i get a effective hit ratio of 37.517/1.458.957 =2,6%  ????
>
>where do the 10% going around come from???
>

I get around 4-8% hits in normal middlegame positions when using plain vanilla
negamax. I've also experimented with PVS and that seemed to increase the hit
ratio a bit (because of the researches I suppose).

There is also the possibility that my numbers are totally bogus. My program is
in pre-alpha stage and I've spent the last couple of days hunting bugs in that
hashtable code.



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