Originally posted by Stalker56
Is this a mate?
The question is, is the position, and white's last move, legal?
It looks like the last move by white must have been e5xd5(en passant), which means, one move before, black's d pawn would have been on d7.
White has 7 white bishops, 2 black bishops and one pawn left, so all white's 7 other pawns must have been promoted to bishops, with 6 promoting on white squares and one promoting on a black square.
White's a pawn would make 1 capture, and promote on black.
Whites b pawn would need no captures, and would promote on black
White's c pawn would make 1 capture, and promote on black
White'd d pawn would make 1 capture, and promote on white
Whites e pawn is still on the board.
White's f pawn would need no captures and would promote on black
White's g pawn would make no captures and would promote on white
And white's h pawn would make 1 capture, and would promote on white.
So that is 4 captures, except we have promoted on 4 black squares and 3 white squares.
We need another 3 captures to convert 3 black square promotions into white square promotions, so white's pawns must make at least 7 captures.
It looks like those captures might be hard for white to manage because quite a lot of them need to be captures of pieces rather than pawns, at this point though, I got stuck, because I couldn't rule out blacks's pawns promoting first and being captured after.