horribly illegal position

Joke problem. White has to mate in one. Only he's touched the knight! how does he mate in one?

Nxg3, Nxf2, Nxd6 or Nxf6 since the position is illegal, why stop there?

Or for that matter, take the king with the rook (lifting your hand off the knight might be illegal but again, where are our boundaries)

Or move another piece, or move the knight to almost any other position on the board.

knight to c3?

edits... changed my answer once or twice.

Originally posted by agryson
knight to c3?

edits... changed my answer once or twice.

Good copying!

well, Nc3 isn't checkmate. Black has Kd4. And here are the rules I'm working by:
At the end of the move, black must be in checkmate.
All pieces must move normally, as they would in normal chess.
You must also abide by the touch move rule and so forth.
No capturing the king.

I don't understand - Black's king is already in check?

The only move white has to do is to turn his head up, meet his opponents eyes and say "Check mate!"

Black can take the knight

Originally posted by doodinthemood
Black can take the knight

No, he can't, it's white's turn.

then it isn't checkmate, it must be at the end of white's turn.

Originally posted by doodinthemood
Joke problem. White has to mate in one. Only he's touched the knight! how does he mate in one?

[fen]8/8/3PpP2/4k2R/4N1P1/B4rR1/1B3PK1/2B5[/fen]

He moves the board with his other hand so the knight ends up on e8!! 😵

EDIT: Crap, still not mate...

After ++Nd2+ then it is mate in 1.

I think the joke is that we are not being asked to find a mate in one, but to find a move that gives us mate in 1.

Nd2+, Kf4

Originally posted by doodinthemood
Nd2+, Kf4

Be5#

that's mate in 2 🙂

Originally posted by doodinthemood
that's mate in 2 🙂

Yes, there is no knight move (except for moves where white takes his own material as Gastel suggested) that gives an instant checkmate. Therefore the only thing white can do to get mate in 1 is get mate in 1 after his move. The alternative is Kxf3, but the preamble suggests that a knight move is necessary.