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Subject: Re: Compiling Crafty's enormous PGN into an opening book

Author: Steven Edwards

Date: 17:27:02 09/24/03

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On September 24, 2003 at 19:54:35, Robert Hyatt wrote:
>On September 24, 2003 at 18:29:05, Steven Edwards wrote:

>>I had my toolkit compile Crafty's 945,950,820 byte enormous.pgn game file into
>>an opening book as a stress test.  The 1,511,728 games required about 14 hours
>>to process and this resulted in an opening book position library with 34,961,266
>>entries.  All positions reached in the first 48 ply for each game were stored.

>I am not sure, but the last time I did this it took about 1 hour on an
>older 500mhz xeon, to read/parse/sort/create that big a book file.  Of
>course, I don't know what kind of disks you are using, mine are always
>SCSI of some flavor...

The total I/O time is only a few minutes, so the IDE/SCSI factor is unimportant
in this case.

Most of the time is spent in the PGN movetext parser.  Unlike a minimal PGN
scanner, the toolkit's movetext parser is performing every kind of check and
normalization possible; this includes a rather vigourous near-SAN to SAN mapper
along with full processing of recursive variations, NAGs, and some features that
may go into the PGN2005 specification.  It even detects the bogus 0x1a byte near
the end of the enormous.pgn file.

The resulting opening book requires O(log2(sqrt(N))) probes to fetch a entry.
This is fast enough to use the book at the upper levels of the search and other
selected interior nodes.



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