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Subject: Re: Tablebase sizes: 6 man? 7? 8? ...

Author: Robert Hyatt

Date: 10:03:53 11/17/98

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On November 17, 1998 at 08:14:45, Mark Young wrote:

>On November 17, 1998 at 08:05:33, Robert Hyatt wrote:
>
>>On November 17, 1998 at 06:35:08, Ralph E. Carter wrote:
>>
>>>Has anyone projected the size of these?
>>
>>
>>easy to do... for edward's format, use 64* size of previous file.  IE for
>>openings with at least one pawn, two files each with a size of 32 gigabytes.
>>
>>Eugene's format is more compact, around 50%.  Still *very* *big*...
>
>How big a factor increase is adding pawns to the table bases that are 6 ,7 or 8
>man.

It really is not a factor.  IE if you have a totally pawnless tablebase, then
a tablebase with a single pawn is bigger, because some of the compression
tricks can't be used or you will make a pawn move in impossible directions when
you rotate reflect and mirror the board.  But once you have a single pawn on
the board, every additional piece is roughly 64 time bigger than the last
one.  Eugene actually beats this a bit, so that since some squares are occupied
(say 5 in a 5 piece ending, going to a 6 piece ending only takes 59* as much
space (if I calculated that right) and not 64* like the old Edwards indexing
scheme...

But it really is moot...  No PC's allow files that large today, because of the
32 bit nature of the processor...  you can't go beyond 4 gigs on any machine I
know of until you step up to the alpha/etc 64 bit architectures...  Yes it is
"possible" to go beyond 4 gigs on a PC, but it makes handling the file index
very messy... and I don't know of a system that does it...



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