Every commenter except one is turning the puzzle upside down, and assuming that the leftmost file is “h” and the rightmost is “a”. I.e., they’re looking at the board from the black perspective. In fact, the board is set up in the standard way, from white’s perspective, with the a file on the left and the h file on the right.
1 … Ra5 is the way to go, as anonymous noted, with good analysis. However, white has another try that needs to be refuted: 2 Kd4 Kb3 3 Kc5 and black might be tricked into thinking he has to repeat with Ka4 to protect the pawn. However, he has: 3 … b4+! and wins. 4 Kd4 Ra7 and black’s winning plan is to: 1. bring his R to the c file to cut off the white K 2. use his K to shepherd the pawn to the second rank 3. use the Lucena technique to promote and win
Chris, the h-file is the leftmost file. You may not be able to see it on your monitor, but there are actually file and rank indicators at the side of the board in the diagram.
This is a great puzzle to play against a computer. Really fine.
The hard part is producing a checkmate in 50 moves.
I did not check whole but for me Rf3 and further pushing Blakc king wins 🙂
I would try and bring the rook to behind the pawn in order to push it.
Something like:
1. Rf3+ Ke4
2. Ra3 Kf4
3. Ra4+ Kf5
4. Ra5+ Kf4
5. Rg5
Yes. Black wins easily as follows:
1. … Ra5 2. Rb7 Ra8 3. Rxb5 Rc8+ and wins the rook and the game.
For any other third move, Black either checks away the king with Rc8+ or advances the pawn to queen.
Every commenter except one is turning the puzzle upside down, and assuming that the leftmost file is “h” and the rightmost is “a”. I.e., they’re looking at the board from the black perspective. In fact, the board is set up in the standard way, from white’s perspective, with the a file on the left and the h file on the right.
1 … Ra5 is the way to go, as anonymous noted, with good analysis. However, white has another try that needs to be refuted:
2 Kd4 Kb3
3 Kc5 and black might be tricked into thinking he has to repeat with Ka4 to protect the pawn. However, he has:
3 … b4+! and wins.
4 Kd4 Ra7 and black’s winning plan is to:
1. bring his R to the c file to cut off the white K
2. use his K to shepherd the pawn to the second rank
3. use the Lucena technique to promote and win
Chris, the h-file is the leftmost file. You may not be able to see it on your monitor, but there are actually file and rank indicators at the side of the board in the diagram.