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Subject: Re: Is there a limit on our ability to compute endgame tablebases?

Author: bob o

Date: 17:53:16 05/28/02

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>>It has been proven a few times that 6-man TBs don't make an engine "smarter", >>it just makes them play a prettier endgame.  The 3/4/5's are really the only >>TBs you NEED to have.
>
>I don't see how such a thing could ever be "proven". First, there's the obvious
>fact that as the number of men in the tablebases increases, the engine's game
>must improve, since if it had access to 32-man tablebases, I think it might >play very well indeed.

The problem, as I understand it, is that the access to the hard drive slows down
the search. So if you had a position where you would get ~500 kn/s without
tablebases, you would only get, say, ~200 kn/s with tablebases. They give more
accurate evaluations for fewer positions, in other words.

>Second, I fail to see why 5 should be some magic number for the maximum number >of men in the tablebases that are "needed" -- why not 4 or 7 or any other
>number? Just because the 6-man tablebases are not yet complete does not render >them any less necessary than 3-4-5.

The 6-man files already generated are generally things like krnknn, which almost
never comes up. The ones that would matter more are the ones with pawns, such as
krpkrp, since these occur in real games more frequently. The problem with
generating tablebases with pawns is that you first need all the related ones
without pawns, such as kqrkqr, kqrkrp, krrkrp, etc.

5 is not seen as a magic number, it's just the largest ones that current
technology allows for.

As an aside, current checkers programs can use 8-man checkers tablebases (the
files are much smaller than chess tablebases). A fast computer can sometimes
analyze a position that is just out of the opening book, and hit the tablebases
on the first move that it searches. It can then know only a few moves into the
game what the result will be, assuming the other program doesn't blunder. This
helps delete losing book lines and improves the opening book immensely, as I
understand.

Bob



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