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Subject: Re: Which set of TBS is most recommendable?

Author: Russell Reagan

Date: 15:47:10 12/01/01

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On December 01, 2001 at 16:35:31, Mike S. wrote:

>After reading the Gandalf-GT 2 match discussion below (partially about problems
>recognising that RN-R, RB-R are usually draws), I'd like to ask what you think
>is the best recommendable (sub-)set of the table bases for practise including
>engine matches.
>
>I'm aware most people will say "use all 5 men tbs", but large experiments have
>been made showing that the slowdown effect and other effects from using the tbs,
>often result in *worse* performances in practical positions, than without the
>tbs. Misjudgement of continuations which keep the game out of tbs material, is
>one of these effects, which i.e. can make the win unecessarily easy for the
>opponent (which may - without tbs - fail to win if the best defense in played).
>
>I use the complete 3- and 4 piece-tables *plus* krnkr, krbkr, because these are
>very important draws. These two should not create an "incomplete" problem
>because they do not contain pawns.
>
>What do you think?
>
>Regards,
>M.Scheidl

I have never understood why the advantages of using tablebases are outweighed by
the slowdown it causes.  Here's my thinking; maybe someone can point out my
error.  As I see it, if you have the complete n-man tablebases and their
subsets, then you can just keep track of how many pieces are remaining on the
board and if a position has n pieces remaining or fewer, then you play whatever
move the tablebase says, since that is the best line.  I don't see how this
slows down anything, unless you're talking about incorporating probing the
tablebases into your search and evaluation of many positions.  I hope someone
will explain this to me, because I've never implemented tablebases into my own
program and I plan to eventually, so I'm sure this will be something I'll need
to know eventually.

Russell



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