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Subject: Re: Auto configurable hash table size?

Author: Robert Hyatt

Date: 07:28:07 06/26/99

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On June 26, 1999 at 05:34:58, Lin Harper wrote:

>      On reading posts re: optimum hash table sizes for various
>    programs and time settings for them, I could'nt help wonder
>    why these programs don't auto adjust their own hash size for
>    the situation they find themselves in as the game progresses.
>      For example, during the opening phase hash is not needed,so
>    the program could only activate the hash when the book runs out.
>    As the endgame approaches and transpositions become more likely
>    then bigger hash would presumably be an advantage, the hash size
>    could adjust itself upwards.
>       This must have been all thought of by clever programmers before
>    and rejected for some reason. Perhaps it's just not possible to
>    do it or the benefit would be negligible?
>       Just a thought, guys.

1.  It is not possible to determine total memory on a computer when they
support virtual memory.  And if you make the hash table too large, performance
will die.

2.  changing the size during the game is also not really great, becaue when
you change it you would have to stop and 'relocate' all the entries, or else
clear it.  Neither of which is worth the time spent.



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