Section D2 – h#3
2 solutions
1.Rb6 Rxf4 2.Rb4 Bb5 3.Rxc4 Bxc4#
1.Bg3 Bxc6 2.Be1 Rf2 3.Bxd2+ Rxd2#
Active sacrifice (black) × 2
Analogy (good)
Exchange of functions (bBf4/bRc6, Captured / Sacrifice)
Exchange of functions (wRf7/wBe8, Guard / Mate)
Orthogonal-diagonal transformation