Author: Alessandro Scotti
Date: 13:52:01 10/08/04
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On October 07, 2004 at 18:55:48, Dieter Buerssner wrote: >... snip > >Assume your opening book has for example the following line. > >1. d4 Nf6 2. Bg5 e6 > >You also have other lines for black with 1. d4 e6. You play with black. After 1. >d4, you play sometimes Nf6, and sometimes e6. The game goes: > >1. d4 e6 2. Bg5?? > >You try all legal moves in this position. And when trying 2...Nf6, you find that >the position is in the book. So you will play out of book Nf6??, now, instead of >Qxg5. Peter Schäfe mentioned, that one should check, that the current position >is also in the book, and if not, search instead of looking for book moves. And >in this small example, it is not in the book, yet. But assume you add another >line to the book. > >1. d4 e6 2. Bg5 Qxg5. > >Now the position after Bg5 is in the book. The position based book move >searching algorithm will find 2 moves, now after 1. d4 e6 2. Bg5?? - Qxg5 and >Nf6. A typical algorithm will play half of the time the stupid move Nf6. I >think, this clearly shows, that a position only based book will not work >reliably in general. In engine matches, this may not be very obvious, because >engines will not make such gross errors like Bg5?? typically. But more subtle >cases are possible. > >... snip Thanks Dieter, this example is really interesting... it seems that one of the nice features of position-based books (transposition) can also become its biggest defect...
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