> In standard chess it's relatively simple, two position are > equal if: > ... > - same castling rights > ... > Scid does not consider the castling rights.
Steve wrote: > But does it make any practical difference ? Definitively yes. It is possible that in a certain position the castling right may change the position evaluation fundamentally. In a certain position the castling may lead to win (avoids mate), but the lack of the castling right leads to a loss (mate is unavoidable). Furthermore the strategy in a game may depend on the castling rights. One example: The right of a short castling may give you the possibility to a pawn storm on the queen side, but often the lack of the short castling right forbids a pawn storm on the queen side. > ie - How many real games do you have with identical board setups but > different castling rights. Above I've pointed out that I'm not talking about the start position. I assume that you're asking about board setups in the middle game. Momently I don't have practical games. With my practical experience the influence by castling rights on the strategy in a game is important, the influence of the castling rights is more important than the influence of en-passant rights. If you assume that the number of real games with equal positions but different castling rights is small, I will agree, nevertheless it is important. The definition of position search rules is a matter of experience (or a viewpoint), and it's not a problem if there are differences between different chess database applications. But with my experience the castling right is important (I was an attacking player, disregarding any safety, but not disregarding the position). The statement > Scid does not consider the castling rights. is only an observation about the differences. This statement is important; for example if you open the database Big2010.cbh (provided by the ChessBase distribution) the opening trees of Scid and Scidb do differ slightly, but that's not an error, it's a different point of view (Big2010.cbh contains some games with unusual castling rights). -- Gregor Cramer email: <[email protected]>
