Author: Marc Lacrosse
Date: 05:37:55 04/06/05
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On April 06, 2005 at 07:10:25, Norm Pollock wrote: >On April 06, 2005 at 06:38:18, Marc Lacrosse wrote: > >>As I tried to build a book from a large PGN database with wincrafty 19.19, I got >>an error message for every game with underpromotion (there was a few ones)and >>the process eventually aborted. >>It was a very clean PGN file from which I could build books without any problem >>for both Yace and Pharaon. >>Did someone else notice this before ? >>Is this a bug ? >> >>Thanks >> >>Marc Lacrosse > >Great observation if indeed this is the case. > >From a realistic point of view, the "underpromotion" is not likely to be used in >an actual game even if it is in the opening book. Well, not for now. But maybe >in 20 years an opening book will make the first 60 moves ;-) >Btw, what is the earliest move number in which the underpromotion took place? I cannot answer (I am not at home) but the book was supposed to be 62 plies long. I do not know whether crafty checks every game beyond this defined number of half-moves. I was myself surprised to see that there were quite a few dozens games with underpromotion in this database. Almost all of them (if not all) are not "true" underpromotions. They are games where a pawn is promoted and is immediately taken or exchanged. The fact that a rook, knight or bishop promotion has been recorded instead of a queen promotion has no signification in such cases as regards further course of the game. Including or excluding these few games has no importance in the book building process. But the problem lies in the fact that the whole process of book creation aborts after crafty finds a few games of this kind. Preprocessing the database for exclusion of underpromotion games should be a solution but this is not an easy task with the various tools that i have. Marc
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