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Subject: Re: Hash collisions with deep searches

Author: Gerd Isenberg

Date: 02:40:35 12/20/02

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On December 19, 2002 at 16:50:32, Dann Corbit wrote:

>Suppose that we are searching at long time control, and the hash table rapidly
>fills up.  This can throw move ordering in the toilet, if we can't find
>transpositions any more.
>
>What sort of replacement scheme is best for very long searches (several
>minutes)?

Hi Dann,

I use a two table approach.

A primary big one, where i replace one of eight with the lowest
timestamp/draft/someFlags priority. Exact entries became a bit more resistance
against overwriting, the same for most left succesors of every root move (pv and
refutations lines).

A smaller secondary one, with an always replacement scheme.

In general i don't store or probe in qsearch. I use IID in __every__ interior
node without a move hint from hash.

Regards,
Gerd




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