Author: Robert Hyatt
Date: 05:45:49 04/04/00
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On April 04, 2000 at 07:40:38, Jan Pernicka wrote: >On April 03, 2000 at 08:42:21, Robert Hyatt wrote: > >>On April 03, 2000 at 05:57:51, Jan Pernicka wrote: >> >>> Hi, >>>I would like to know how to make opening book(OB) "run" in memory (MEM) >>> as efficient as possible. >> > >>Store hash keys _after_ each move... then you don't store 'moves' in the book >>at all. You store hash keys that are produced by making specific moves. To >>find a book move, generate all legal moves, make each one, and probe the book >>after making the move. If you get a hit, this is a book position. Repeat for >>all legal moves to get the set of known book moves... >> >>Doing it in constant time is also easy. See crafty's source (book.c). > > > Thank you, > > but I have yet several questions: > > When do you throw away the book from memory? (not found any moves > for 3 positions there ?) I don't read the book into memory. I read 'chunks' as needed, and I let the operating system cache stuff to make it fast. I give up on the book after three successive moves don't find a book move... > > How big hash table should be used for book? > (there can be conflict between "normal" hash table and "openning" > hash table(in their sizes) - they can be present in memory at the same > time - but only if answer to my previous question is not "1" ... ) > > Thanks, > I don't use a hash table. I 'pack' the book positions together into one file, and then read pieces of that as needed... this way the file is not a 'sparse' file with lots of empty space in it... > Jan > >PS: In fact, your method finds a move in time proportional to number of moves > generated from that position, which could be said to be constant... :)
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