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Subject: Re: Why max Hashtable Limit for Fruit is 1024 ?

Author: Günther Simon

Date: 04:49:35 11/24/05

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On November 24, 2005 at 05:17:24, chandler yergin wrote:


>  Hash is automatically set by the Processor speed.. what is optimum and Max for
>the system being used. Right click on the Engine in the analysis window.
>The Menu tells you what that is. If you try to exceed that you get a Warning
>that it will slow down performance.
>In Blitz you want speed. Min Hash! 1 Mg is fine.
>As was noted by another Poster.. simply Set Max Hash and read the kn/S
>Reset to 1 Mg Hash and check Kn/S    No comparison!
>Long games you need large Hash.
Hash tables

Another Chessbase manual mantra in contradiction
to your obviously old CB mantra:(from F8)
(The truth of course is even more complicated and beyond
CB manuals)
--------------------------------------------------------------------------------

Hash tables are memory areas in which the program can store positions and
evaluations while it is calculating the moves of a game. If the program
encounters the same position again, it can simply take the evaluation from the
hash tables, rather than analysing the position all over again.
(of course not clearing hash to save the already calculated infos, like
told above! G.S.)

Hash tables increase the playing strength of the program considerably. This is
especially true of tactically strong engines like Fritz, Junior or Nimzo. Some
run at well over 500,000 positions per second, and will fill the hash tables
very quickly. After that, the search slows down. This is not the case in a
slower, positionally oriented program, which processes less positions per
second, and takes much longer to fill the hash tables.

For slower time controls and deep analysis the engines need large hash tables.
Tournament games with an average of three minutes (180 seconds) per move would
ideally require over 256 MB for the hash tables. On blitz levels four to 64 MB
is enough. (for machines in 2002/3! G.S.)

Some engines work best with hash tables sizes that are powers of two. This means
that 64 MB of hash tables is much more valuable than 63 MB. Hash table sizes are
set in the "Load engine" menu. (for machines in 2002/3! G.S.)

--------------------------------------------------------------------------------

Nothing of 1Mb hash for Blitz, nothing of clearing hash between moves, even
Chessbase sometimes updates their manuals ;)
And for an extro info for you even this hash sizes are now outdated as
processors again gained speed in the last years, which means _more_
hash today again...

Guenther



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