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

Author: Dan Homan

Date: 11:20:00 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 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???
>
>can anybody explain, how he counts and what numbers he get?

I think that most people are counting like you do.  It depends on
whether you store/probe frontier or q-search nodes.  I never store
or probe for q-search nodes, but I have tried it both ways with
frontier (depth = 0) nodes.  When I probe but do not store frontier
nodes, I find that I get about 1% to 5% efficiency in most positions.
When I probe and store frontier nodes, I get 10% or better efficiency,
but this seems slower overall than only probing frontier nodes.

 - Dan


>
>Greetings
>
>Werner



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