I expand Eric's position to ....k..r p.p.p.p. .p..P... ........ ...R.... ......P. .....P.P R...K... If Black's castling move is unavailable, then R/a1-d1 followed by R/d4-d8 mates. I'm having trouble establishing that Black can't castle. Assuming that his k and r have never moved, his previous move to arrive at this position must have been p/b7-b6. To back up further, we must assume that White's previous move captured a Black piece (or pawn). Let's say it was R x n/d4. From this position, I think we can fairly mechanically work backwards, with Black's queenside pieces developing through d8 or d7, his knights developing normally, and White capturing Black's kb at f8 with a knight. The WN can get to f8 and back out without giving check to the bk/e8. Incidentally, in the diagram position, White must have moved his K to allow the KR to escape -- again, assuming the bk and bkr have never moved. If White created a third rook by underpromotion, there's no escape path from the 8th rank that doesn't check bk. Rich ------ Quoting Eric Angelini <eangelini@everlastingprod.be>:
Bill & alii, here is a really tricky mate in 2.
4k2r / p1p1p1p1 / 1p2P3 / 8 / 3R4 / 6P1 / 5P1P / R3K3 /
Best, Éric.