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Subject: Re: hash tables

Author: Kurt Utzinger

Date: 09:03:24 12/20/03

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On December 20, 2003 at 11:44:54, Uri Blass wrote:

>On December 20, 2003 at 11:21:26, Kurt Utzinger wrote:
>
>>On December 20, 2003 at 11:03:04, scott farrell wrote:
>>
>>>On December 20, 2003 at 10:53:56, Jay Hysenbeg wrote:
>>>
>>>>hi,
>>>>i was wondering what happens when u use low hash for a long time control. to the
>>>>point where the hash is normaly filled before the eng has made its move.
>>>>thank you
>>>>jay h.
>>>
>>>well, things start to deteroriate, your move ordering isnt as good etc., and
>>>your branching factor ends up so bad that it cant get from say 10 ply to 11 ply
>>>or whatever, it sort of like hits a brick wall somewhere.
>>>
>>>To what extent this happends largely depends on your replacement scheme, and how
>>>well it deals with overwriting entries.
>>>
>>>I test changes to my hash by running extremely small hashes, like 16k entries,
>>>just to see how it will cater.
>>>
>>>Scott
>>
>>     Size of hash tables seem to have much less influence
>>     than I have imagined. This showed a test over 50 games
>>     between Fritz 8 [96 MB hash] against Junior 8 [8 MB hash]
>>     and a second 50 games match Fritz 8 [8 MB hash] vs Junior 8
>>     [96 MB hash]. The final result was in both matches almost
>>     identical [25m+10s].
>>     Kurt
>
>It is possible that 8 MB is already almost enough for your time control.

     Maybe, I have no idea. And furthermore: 2 x 50 games are most
     probably not enough to prove something.
     Kurt
>
>It is possible that 96 MB is only 10 elo better than 8 MB at the time control
>that you tested but if you use 12 MB against 1 MB you get bigger
>difference of 25 elo.
>
>I do not expect more than 25 elo based on upper bound of 7 elo for doubling the
>hash tables.
>
>Even if the difference is 24 elo then it means that you can expect only
>26.5-23.5 for the stronger side in 50 games and the statistical error in a match
>of 50 games is more than 1.5 point.
>
>Uri



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