Author: José Carlos
Date: 06:01:52 05/24/01
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On May 24, 2001 at 08:57:43, Robert Hyatt wrote: >On May 24, 2001 at 08:55:15, Pham Minh Tri wrote: > >>On May 24, 2001 at 08:14:37, Gian-Carlo Pascutto wrote: >> >>>On May 24, 2001 at 07:50:32, Pham Minh Tri wrote: >>> >>>>Hi, >>>>I heard that the hash technique could apply to opening book. Could someone >>>>explain to me how to use and what is the benefit? >>>>Thank very much in advance, >>>>Pham >>> >>>Quite simple. Instead of storing positions or sequences you store >>>the hashes of the positions. >>> >>>The benefit is space. If you were storing sequences you will also >>>spot transpotions now. >>> >> >>Could you explain more detail? I still do not understand. The 64 bit hash key is >>always bigger than 16 bit of a move representation, and the random numbers may >>make the hash key after moving totally different from the old one, so how to >>save space? >> >>And another question: does this technique need more computing (to match and >>extract) than the normal technique (use other kind of database)? >> >>Thanks, >> >>>-- >>>GCP > >To build the book, make the first move in the book line, say e4. Store the >hash signature _after_ that move is made. Then for other first moves (say d4) >do the same. > >When you want to use the book, generate all legal moves, make each one, one >at a time, and after making one, check to see if the current hash signature >matches a signature in the book file. If so, this move is a "book move". And (to Pham) do not forget to use _always_ the same random numbers to generate the hash keys :) The biggest benefit of this technique is that it makes trivial to handle transpositions. José C.
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