Author: Mike S.
Date: 16:08:41 07/20/02
Go up one level in this thread
On July 20, 2002 at 12:05:44, Russell Reagan wrote:
>My question is, what SHOULD an engine or GUI do when it recieves something like
>this?
Maybe it would be best, when chess programs have an option to insert illegal
moves when games are *entered* (not while playing games). When such a gamescore
is pasted, or read from a new file, a message could pop up and ask the user
something like
"Illegal move 18...O-O-O detected!
-> Accept
-> Skip rest of the game
-> Try to skip illegal move only?"
When opening a PGN containing John's example with SCID 3.3, it displays an
import message pointing to the game and the illegal move. Then, it is possible
to replay the game only until 18.cxd3. If there was no original comment at that
point, SCID displays "Error reading move: O-O-O". - By that, problems with
database integrity/legality check in the target (non-PGN) database are avoided;
the user would have to solve the problem in the PGN source himself.
Shredder 5 ("classic" GUI) behaves similar. I can open the PGN file, but when I
load the Dominguez-Nilsson game, a message pops up saying "Illegal move O-O-O",
and the last move visible is 18.cxd3.
But it's difficult to solve, when it isn't just an entering error, IOW. the
illegal move has really been played. Illegal moves will unavoidably appear then
and when in human games. John's example is typical IMO. AFAIK FIDE rules cover
only the situation when an illegal move is found while the game is in progress;
I can't find a rule at the moment about illegal moves discovered *after the game
has ended*. Probably there is none?
It is a problem especially for chess database programs, but of course also for
the database part of playing programs. The current alternatives (if you'd have
to enter such a game) to either skip parts of the game, or to include the moves
as a text comment, is not 100% satisfying.
It looks like many programs will accept an illegal move when loeading a PGN file
though. I can open the PGN of the example with ChessBase 7.0 (default PGN
application on my system) directly from the PGN URL, save it to local PGN and
also open it completely in Fritz 7. - But when I step through the game in
analysis mode, "X" pieces appear in the pv after the illegal castling...
I've read there has been a game Karpov - Kasparov where Black promoted his black
pawn to a *white* queen and Karpov immediatly used his new piece giving check,
in his reply... :o)) unfortunately I can't find that game currently. If this is
true, it would be another nice example.
Regards,
M.Scheidl
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