Another 'take back and mate' problem

M.Caillaud

White takes back a move and mates in 1 instead.
What were the last 3 single moves?

I'm not even sure how the white rook got to a8, but here goes:

Take back f7xQe8=Q and replace with f7xNg8=N++

Originally posted by SwissGambit
M.Caillaud
[fen]R1brQnnB/pp1pk2p/3pp1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]
White takes back a move and mates in 1 instead.
What were the last 3 single moves?

nvm

Originally posted by rogilvie
I'm not even sure how the white rook got to a8, but here goes:

Take back f7xQe8=Q and replace with f7xNg8=N++

The white rook was promoted on f8. an uncapture of a knight is illegal because black still has all 8 pawns. The rook had to be promoted on f8 because after white uncaptures on e8 there is only one retraction for black -1...cxd6 and only one capture made by white and that would be needed to get two pawns on the f file.

Originally posted by tomtom232
The white rook was promoted on b8. and an uncapture of a queen would make an illegal position but if its a knight its also illegal because black still has all 8 pawns.

Almost solved - just need the last 3 single moves.

Originally posted by SwissGambit
Almost solved - just need the last 3 single moves.

So uncapture a rook.



i don't know what to uncapture on c6 though



how about a pawn because anything else and black won't have a retraction.



and then the last single move before that whould be c5c6

Originally posted by tomtom232
So uncapture a rook.

[fen]R1brrnnB/pp1pkP1p/3pp1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

i don't know what to uncapture on c6 though

[fen]R1brrnnB/ppppkP1p/31p1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

how about a pawn because anything else and black won't have a retraction.

[fen]R1brrnnB/ppppkP1p/3Pp1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

and then the last sin ...[text shortened]... ve before that whould be c5c6

[fen]R1brrnnB/ppppkP1p/31p1p1/3P2N1/6Kp/8/8/8 w - - 0 1[/fen]

It can't be a rook uncaptured on d8, since there's no way out for a rook from a8. So must been a queen uncaptured there since the only other captured black piece is a dark squared bishop. So we have



Last black move can't have been the pawn capture, as then there's no way for whites rook to get where it is, so black's last move must have been Kf6-e7, making white's prior move Pg7xBh8=B+



I think this works

Originally posted by Piisgood
It can't be a rook uncaptured on d8, since there's no way out for a rook from a8. So must been a queen uncaptured there since the only other captured black piece is a dark squared bishop. So we have

[fen]R1brqnnB/pp1pkP1p/3pp1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

Last black move can't have been the pawn capture, as then there's no way for whites rook to ge ...[text shortened]... h8=B+

[fen]R1brqnnb/pp1p1PPp/3ppkp1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

I think this works

Yeah thats right. I knew there was a problem with mine just didn't know what.

Originally posted by Piisgood
It can't be a rook uncaptured on d8, since there's no way out for a rook from a8. So must been a queen uncaptured there since the only other captured black piece is a dark squared bishop. So we have

[fen]R1brqnnB/pp1pkP1p/3pp1p1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

Last black move can't have been the pawn capture, as then there's no way for whites rook to ge ...[text shortened]... h8=B+

[fen]R1brqnnb/pp1p1PPp/3ppkp1/6N1/6Kp/8/8/8 w - - 0 1[/fen]

I think this works

Right.

Note that white promotes to all four different types of pieces [allumwandlung], and each pawn captures a piece and promotes to that same piece type [fxQe8=Q, gxBh8=B, fxNg8=N]. c7xRb8=R is how that pawn promoted, because Ra8 is the only piece left after you retract the 3 moves.