Hardest Checkmate in 1

I don't know.

Final position:

???

Lola mentioned "in 1974".

yes ! thats it eric !! wonderful !

the pawn on e7 promotes to a rook. the king hasnt moved. and neither has the rook. castling at that point wuz not breaking the rules ! Tim Krabbe presented this to the FIDE-USCF rules boards and they both did a rewrite in June of 1974. and i dont believe this ever happened in a game.

okay one more & then im done. white to mate in two.

Castle kingside and Rf3#

u hava 66 puzzle rush ? omg !! lol !

and yes u got this one too  .

And after publishing his "Schaak curiosa" book Krabbé admitted he knew that the rules he misquoted didn't permit this weird castling move before publication either. Nothing to do with rules boards. But why let the truth get in the way of a good story?

The oldest version of the handbook I could find is of 1977 so I am not sure of earlier versions. Considering that Krabbé later admitted intentionally omitting the part "on the same rank" in his book quote we may assume the preceding rules were the same:

(FIDE laws 1977) on executing castling:  the king is transferred, from its original square, two squares toward either rook on the same rank; then that rook toward which the king has been moved is transferred over the king to the square immediately adjacent to the king.

I think the majority of chess players learn castling without paying attention to the "same rank" clause. They probably learn all the other conditions of castling but automatically assume castling with the same rank rook without realising that the absence of this clause allows castling with a newly promoted rook to be possible.

Yep It's good practice to reread the rules when you are asked to apply them to an unsusal claim or situation.

Interestingly I found some more tidbits of data on this issue in a dutch article I won't bother to link for you.

(a) The correct definition with castling only by rooks on the same rank as the king was already in place since 1931!

(b) Tim Krabbé's (and Max Pams) joke in the nineteenseventies was repeated in 2008 when the FIDE rules commission was faced with a request to change the rules to prevent the elongated castling move. Without ever reading and understanding its own rules (see my last post), both the commission and the general assembly blindly decided to amend the castling rule into its current form. Which of course changed nothing compared to its crystal clear 1931 predecessor!

Cool.

dxe6# (en passent) if the last move was e5 or else there is no way to checkmate in one move

R F7, K H8, Q F6

R F7, K H8, Q F6 because its impossible to checkmate in 1 move

If the black interposes the bishop, the v will capture the bishop from the queen on the support of the rook.

* then v will

yeah

https://www.wfcc.ch/1999-2012/codex/

Here's what it says in the Official Codex for Chess Compositions...

(which means that the op's puzzle is valid azziz mine in #67)

Chapter IV: Article 16 - Castling and En-Passant Capture

(1) Castling convention. Castling is permitted unless it can be proved that it is not permissible.

(2) En-passant convention. An en-passant capture on the first move is permitted only if it can be proved that the last move was the double step of the pawn which is to be captured [20].

(3) Partial Retrograde Analysis (PRA) convention. Where the rights to castle and/or to capture en-passant are mutually dependent, the solution consists of several mutually exclusive parts. All possible combinations of move rights, taking into account the castling convention and the en-passant convention, form these mutually dependent parts. If in the case of mutual dependency of castling rights a solution is not possible according to the PRA convention, then the Retro-Strategy (RS) convention should be applied: whichever castling is executed first is deemed to be permissible.

(4) Other conventions should be expressly stipulated, for example if in the course of the solution an en-passant capture has to be legalised by subsequent castling (a posteriori convention AP).