Zagoruiko theme

The Zagoruiko theme presents multiple changed mates. A mate is a move that leaves the king attacked with no legal reply. At least two identifiable Black defenses must remain the same, and White must answer each one with a different mating move in each of at least three phases. A defense is Black's reply to White's idea; a phase is a separate section of content, such as the actual solution or a hypothetical line that nearly works.

Minimum pattern

• In phase one, defense a is met by mate A and defense b by mate B.
• In phase two, those same defenses receive two new mates, C and D.
• In phase three, they receive different mates again, E and F.

The letters are only labels. What matters is the stable relationship between the same defenses and White replies that change from phase to phase. One changed mate, or only two phases, is not enough for the basic form.

The phases may combine virtual play, made of structured hypothetical variations, with actual play. Generalized descriptions use n×m, where n is the number of phases and m the number of changed mates. Cyclic forms reuse mating moves in a rotating order while preserving the required defensive framework.