Author: Andrew Dados
Date: 13:31:06 01/29/02
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On January 29, 2002 at 14:35:56, Dann Corbit wrote: >On January 29, 2002 at 14:11:47, Uri Blass wrote: >[snip] >>>No. His notion is that if you mirror using every symmetry, the total number of >>>those positions (including ALL reflections) would be less than 2^81 in that >>>category. >> >>If this is his point then he is wrong. >> >>The number of reflection of the same position is only 4 so the total number of >>classes of 4 positions is only 1/4 of the number of positions and it cannot be >>less than 2^81. > >I was unclear. You should read his document. It also included all motions of >the sliding piece to the winning position. Be aware that this system does not >produce a sure best move. It could be thought of as producing a winning bound. > >If you look at the list of positions Les posted, all 44 of them were generated >by a single position. I suppose if you read the document: >ftp://cap.connx.com/pub/les/cp.doc >it will be immediately clear to you. > >It could also be used to produce alpha/beta bounds for moves that are analyzed. >Again, it might not produce the best possible move. But it could produce a >bound that you know it cannot be worse than that. So, in a sense, it could also >be used to create an inexact information database for move choices. > >You would get similar compressions for arbitrary positions at the beginning of a >game. For pawnless endgames with Rooks, Queens or Bisops it is an attractive idea. For pawn only endgames I don't see much gain if any. How would you store/retrieve from such a database efficiently? Some sparse arrays? String collection? Any SQL would kill you performancewise. -Andrew-
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