Weekly Problems 2026-A

All three white line-pieces may be expected to contribute to the mates, even though each one seems passively placed away from the black king at first. White activates a pair of them in two moves, while the third piece is utilised as a guard when it’s approached by the king (which on e4 has too many flights). After 1.Kd3, Black can block the sole flight on e4 with various pieces, but the rook is selected as the move simultaneously opens a line for the white bishop to give mate – as long as the rook is stopped from returning to e2 by a pin. 1…Qg6+ 2.Re4 Bf1. The other two solutions follow the same pattern, with different black pieces blocking e4 to open other mating lines. 1.Kd5 Bg2+ 2.Sce4 Ra5. 1.Kf4 Ra4+ 2.Sfe4 Qf7. The three white pieces cyclically switch their functions to (1) guard flights, (2) pin the e4-piece, and (3) deliver mate.

Andy Sag: In each case, Black moves king, White checks, Black self-pins a piece on e4, White executes a pin-mate. Well-coordinated solutions.
Jacob Hoover: Not only is there a pin-mate in each of the three solutions, but also across the solutions the three white line-pieces exchange roles in a cyclic fashion between guarding, pinning, and mating.

Since checking is forbidden, White cannot move the rook or bishop in part (a), and stalemate is achieved by using the king to mop up most of the black units. 1.Ka2 2.Ka3 3.Ka4 4.Ka5 5.Kxb6 6.Kc7 7.Kxd7 8.Ke8 9.Kxf7 10.Kxg8 11.Kxh7 12.Kg6 13.Kf5 14.Kxe4. In part (b), the white king can release the other two pieces by interposing on c3/d4; however, the number of viable stalemate configurations remains limited. Akin to the first solution, the rook aims for e5 where it restricts the black king while being protected by the bishop. 1.Kc2 2.Kc3 3.Re2 4.Rxe4 5.Re5 6.Kxc4 7.Kc5 8.Kxb6 9.Kc7 10.Kxd7 11.Ke8 12.Kf8 13.Kxg8 14.Kxh7. The two ideal-stalemate positions are near-exact echoes, placed well apart – an uncommon theme in series-movers.

Andy Sag: Both parts end with the same configuration in different locations. Apart from check avoidance, the black rook dictates the move sequence as it must be captured to allow the white king access to the 7th and 8th ranks.
Jacob Hoover: The two final positions are echoes of each other. This one was quite easy as series-movers go.
Satanick Mukhuty: Neat!