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Subject: Re: Weird things with hash tables.

Author: Will Singleton

Date: 23:05:10 02/23/99

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On February 23, 1999 at 23:42:41, James Robertson wrote:

>I have added what I think are hash tables. But, there are several things that
>have me worried: the biggest is that the pv will often change, e.g. in ply 6
>without hash tables one move will be chosen while in ply 6 with hash tables
>another will be chosen. Is this normal?
>From the starting position I am getting maybe 31% hash hits if the q nodes are
>not counted.
>I am getting almost 1 ply extra on average if I set the tables to 2 ^ 18
>entries. Are these normal?
>
>Thanks,
>James


An extra ply sounds about right, though 31% hash hits is higher than I get.  But
my tables are weird, anyway.  My pv changes if I take out the tables, but I've
got some other things dependent on them, so don't know if that is relevant to
you.  But the eventual best move and pv should stabilize, and you shouldn't get
radically different results.

I use 2^18 for testing, then run 2^20 for server play.  But there's little, if
any, difference between the two, performance-wise.  Do you note any difference
with larger tables?

Will



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