Selfmate problem

Question

[FEN "8/7P/8/p2p4/P2p4/pB1p4/3P4/k2K4 w - - 0 1"]

Composed by IM Geir Sune Tallaksen. White moves first, and must force Black to deliver checkmate. Give the sequence of moves that force Black to mate White on the 7th move!

Answer 1

Neat:

[FEN "8/7P/8/p2p4/P2p4/pB1p4/3P4/k2K4 w - - 0 1"]

1. Kc1 a2 2. Bc2 dxc2 3. h8=R! d3 4. Rb8 d4 5. Rb4 {And from here on, both sides' moves are legally forced.} axb4 6. a5 b3 7. a6 b2#