Rook vs Bishop: The Dangerous Corner

With no pawns on the board a bishop usually draws against a rook, and even a king pushed to the edge is safe. There is one exception, and it decides this ending.

Two corners, two verdicts. The safe corner is the colour opposite the bishop, where the bishop shields the king's escape squares. The dangerous corner is the bishop's own colour, and a king imprisoned there is lost. Run the same squeeze at the dark corner and the defender runs out of moves, a losing zugzwang; run it at the light corner opposite the bishop and the identical position is stalemate, a draw. One square of difference decides everything. And the rook on f7 is what nails the king in place: take it away and the king simply steps to f8 and escapes.

The pawn is a lever, not a queen. The g6 pawn blocks its own king out of g6. The winning move is 1.g7, forcing the king to h7, and after 2.Rf7 the pawn promotes with check and is immediately captured: 3.g8=Q+ Kxg8. That was the plan. Now 4.Kg6 takes the square the pawn was hogging, and the king and rook squeeze Black toward h8.

The pawn is still what wins. Remove it from the diagram and the tablebase says draw. It wins by deflecting the black king to g8 and vacating g6, not by queening.

In this drill the defender runs for the safe corner at every chance. Cut off the retreat and steer the king into its own bishop's corner.