09 Nov '06 19:23>
Puzzle: Find a legal chess position in which we can conclude that at least one of the players has castled, but we can't know which.
Originally posted by crazyblueI think I can reach that position after white's 14th move (you can add a few extra ones if you want!), without castling, so I don't think it solves the problem.
Position after move 18 from White. I'm not sure, but I don't think you can tell who castled. However, I'm afraid you also can't conclude that one site has actually castled.
Originally posted by Mephisto2I don't know how to post a board but, starting from this position, try removing all 4 pieces on the Q side from both sides.
[fen]rnbq1rkn/pppppppp/8/8/8/8/PPPPPPPP/RNBQ1RKN w - - 0 11[/fen]
I think they both castled.
But that doesn't solve the puzzle, does it?
Originally posted by crazyblueWhat about rook moves to compensate that?
I'm pretty sure I just found the solution while thinking about it in the bathroom 😀
Here's it in theory:
- Both sides only make knight moves (and king move/s of course). This is important because knights can't make tempo moves.
- The Bishops and Rooks and Kingside will be captured and the Kings will be on g1/g8
- If both sides castle that wil er) that the kings made 3 halfmoves, which means 1 side castled and 1 didn't.
Originally posted by ilywrinYech, forgot about those. If both sides castle, its not possible, but if both sides do not castle, you can even the halfmoves to 4 and that's it for my solution. And even more, once the king is on g1/g8 and rook+bishop are gone, the queen has two squares to odd/even the moves.
What about rook moves to compensate that?
The more I think about it, the more it seems that this is not a matter of odd/even number of moves since that is easy to get around. I am still clueless as to what else we can use.