Author: Dieter Buerssner
Date: 08:36:27 11/12/01
Go up one level in this thread
On November 12, 2001 at 09:37:23, Robert Hyatt wrote:
>On November 11, 2001 at 21:42:56, Jeremiah Penery wrote:
>
>>On November 10, 2001 at 15:02:15, Robert Hyatt wrote:
>>
>>>Actually it may be bigger. 200mb is the size of the compressed tables. The
^^^^^ ^^^^^^^^^^
>>
>>The size of the "four" directory on your FTP site is only about 30MB. If you
>>store only W/L/D instead of distance to mate, you must be able to save at least
>>half that much space.
>
>
>They are compressed, remember.
Yes. But Jeremiah rightfully pointed out that your number above is wrong.
>And most are full of nothing but zeros (draws)
>which compress to almost nothing. But for win/lose/draw it is not clear that
>you would want to have them in a compressed form as the decompression would
>be expensive, suddenly, since there would be no I/O if they are locked into
>memory. If they are uncompressed, they are over 200 megs (from memory, I have
>not done this in a long while). My first guess was that you end up with 50+
>megs, if not more, assuming you don't compress the 3/4 files...
I don't know the compression ratio of the 4-men tables. However, I think, that
it may be not that difficult for a modern computer, to store all of the 4-men
tables in memory uncompressed as win/draw/loss, when using the same indexing
scheme of the Nalimov tables. For the tables, where both sides can win, the
space advantage compared to uncompressed Nalimov tables would be a factor of 5.
In 1 byte, one could store 5 positions because 3^5 < 2^8. Many tables would only
need win/draw or loss/draw, which makes a factor of 8. Other tables may not be
needed at all. For example KQQK with the Q side moving is allways a win (at
least I think so). With the lonely K side moving, a table look-up may be
substitited by a stalemate detection routine. Depending on the program, this can
also be fast.
Actually, using such w/d/l tables might mix very well with the interior node
detection schemes discussed by Heinz.
Regards,
Dieter
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