Computer Chess Club Archives




Subject: Re: The King "Leiden" - Chesstiger 15 "normal" Now 6,5 -8,5 90 min blitz

Author: Johan de Koning

Date: 23:21:33 05/26/03

Go up one level in this thread

On May 26, 2003 at 11:22:09, Kurt Utzinger wrote:

>On May 26, 2003 at 02:40:49, Andre van Ark wrote:
>>On May 26, 2003 at 02:06:37, Heinz-Josef Schumacher wrote:
>>>>If you want my opinion it doesn't make any sense. Or I need a good explanation,
>>>>and some evidence.
>>>Exact my opinion! This rumour is in Germany in many heads, but without any
>>>evidence! More than 32 MB hash tables perhaps not useful for the King, but not
>>>bad! People had only misunderstood an old statement by Johan.
>>Good day,
>>32 MB is being used because Johan used in Leiden 30 MB.
>>Kind regards,
>>Andre van Ark
>    From own [old] tests under CM9-GUI in the analysis mode, I can remember
>    that some positions could not be solved at all or not within reasonable
>    time if hash tables were set higher than 32 MB hash.

That's very well possible. The search trees explored by competitive engines are
pretty shaky. As opposed to research project engines, whose trees are only
mildly shaky. Tiny details, like TT size, can change the shape of the tree
considerably, especially in endgames. We (engine developpers) don't like this,
but are somewhat relieved by the fact that it averages out.

>    This may however be
>    no longer a problem after the second patch has been released [I have
>    however not investigated this]. And as Andre stated: Johan de Koning does
>    not seem to use more than 32 MB hash and there must be some reason for that.

There used to be a reason: under native DOS (eg 6.2) Watcom's DOS extender
supported no more then 32 MB total memory. :-) So I set TT to 30 MB (30*2^20).
On my latest machine TK runs fine under DOS98, without RAM size limitations.
But 30 MB is simply enough for game in 90'. I'll have to do several test runs
again though on my next new machine.

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