Author: Eugene Nalimov
Date: 12:34:15 11/17/98
Go up one level in this thread
Very rough estimation:
Pawnless 6-man ending - 10**10 positions.
6-man ending with pawn(s) - 2.5*10**10 positions.
8 bits per position is not enough, 9-10 bits necessary.
So, pawnless 6-man ending will use 20Gb, ending with pawn(s)
will use 50Gb.
It's possible to handle huge files at PC using NT (there is
no such restriction on file size as in Linux), but to be
reasonable effective generator must use 1-2Gb of RAM (I'm
speaking not about my generator, but about generator that
is written especially with 6-man tables in mind). Also, you
must have necessary amount of disk space free.
The hardest part will be generation of pawnless endings -
endings with pawns can be partitioned to a lot of subclasses,
depending of the pawns locations.
Of course you can
(1) Generate on a powerful supercomputer (BTW, task can be
parallelized very well), compress table, transfer compressed
table to PC, and decompress only small chunks when necessary.
(2) Generate not DTC or DTM, but win/draw/loss table -
then you can pack 5 positions per byte.
(3) Generate some subclasses - e.g. with rammed pawns, or
with 2 identical pieces, etc.
Eugene
On November 17, 1998 at 13:03:53, Robert Hyatt wrote:
>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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