Author: Robert Hyatt
Date: 19:37:10 09/03/05
Go up one level in this thread
On September 03, 2005 at 19:39:56, Kevin K wrote: >On September 03, 2005 at 18:11:23, A. Cozzie wrote: > >>On September 03, 2005 at 18:06:05, Robert Hyatt wrote: >> >>>On September 03, 2005 at 17:05:36, Kevin K wrote: >>> >>>>Hello, Dr. Hyatt. >>>> >>>>1 d2-d4 d7-d5 2 e2-d4 >>>>1 e2-d4 d7-d5 2 d2-d4 >>>> >>>>These two moves are considered the same in transposition table, >>>>because resulting positions are the same. >>>>But, what about in book database? >>>>As far as I know, Crafty does not consider these the same positions in book. >>>>Why not? >>>>For example, if I have only 1 d2-d4 d7-d5 2 e2-d4 e7-e6 in book and >>>>if I play 1 e2-d4 d7-d5 2 d2-d4, Crafty does not find next move(e7-e6) >>>>from book even though two positions are the same. >>>> >>>>Thank you. >>> >>> >>>A book position is based on the parent position and the child position. That >>>is, the position before the move and the position after the book. >>> >>>This was done to avoid a well-known transposition "bug".. >> >>Probably not well known to him, Bob :) >> >>If you do the book purely based on position you can get problems like this >>example (the program being black) >> >>1. e4 e5 2. Bb5 a6 3 Nf3 Nc6?? >> >>anthony > >I know what you mean. But, >1. e4 e5 2. Nf3 Nc6 3 Bb5 and >1. e4 e5 2. Bb5 a6 3.Nf3 are different positions. >Positions just before final position must be the same. >This doesn't seem good example. You miss the point. The fact that they are different positions is the reason I do it that way. Otherwise the two positions are identical, and you just played a book move as black, rather than ripping my free bishop. That is what my book format avoids...
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