Weekly Problems 2026-B

The white king has four diagonal flights, and the two eventual mating moves by Black’s queen and e8-bishop will cover different pairs of these squares. In both cases, White needs to self-block the two remaining flights, so the rooks are unpinned for this purpose. The white queen and h7-bishop take turns to unpin one of them, which then frees the other. Once both rooks have carried out their self-blocks, the self-pinned queen or bishop moves along the pin-line to give a deflecting check, which forces a diagonal pin-mate. 1.Qh1 2.Qc6 3.Rd4 4.Rc4 5.Ra2 6.Ra6 7.Qd7+ Bxd7 and 1.Bg8 2.Bc4 3.Re6 4.Rc6 5.Ra7 6.Ra4 7.Bd3+ Qxd3. Two attractive sequences with perfectly matching effects, including how the rooks switch the lines on which they are pinned.

George Meldrum: Nice pair of complementary solutions. Had initially thought that a king march may have done the trick: Kc6-d6-e7-f8-g7-h6-h5, Qh3+ Qxh3, but alas that was eight moves.
Andrew Buchanan: Very satisfying. The unguarding and re-guarding of the white squares adjacent to the black king is particularly cute.
Satanick Mukhuty: Beautiful harmony of unpin and self-pin in the two phases!