No.13 | by Peter Wong
Changed play represents one of the essential ideas in directmate problems, especially two-movers where it is most frequently found. In response to a certain black defence, White makes a move in the actual play that is surprisingly different from that in another phase, such as set play and try play. This concept of changed play is intensified in the Zagoruiko theme, which specifies a framework of changed variations. A two-mover demonstrates a Zagoruiko if the following scheme occurs: at least two black defences lead to changed white mates, with each defence provoking at least three different white mates in separate phases. The theme is named after a Russian composer who devised some notable examples in the 1950s.
73. Ottavio Stocchi
Raccolta Completa dei 933 Problemi di Ottavio Stocchi 1995
Mate in 2
In Problem 73, the thematic defences are 1…Sg6+ and 1…Be6. As already arranged in the diagram, 1…Sg6+ allows 2.Qxg6, and 1…Be6 allows 2.Rxe6. The try 1.Qf4? (threat: 2.Qe5) abandons these set mates and changes the play to 1…Sg6+ 2.fxg6 and 1…Be6 2.fxe6. But 1…Sf7! refutes the try. The key 1.Qe4! (2.Qe5) also disrupts the set play, and substitutes yet another pair of mates, 1…Sg6+ 2.Rxg6 and 1…Be6 2.Qxe6. (Or 1…Sf7 2.Rg6.) The three parts are unified by the recurring white captures on g6 and e6 by various pieces. This example shows the Zagoruiko in its basic 3x2 form: 3 phases (1 set + 1 try + 1 actual) x 2 defences.
74. Miklós Locker
64 1971, Special Prize
Mate in 2
Problem 74 is an economical miniature, which denotes a position with no more than seven pieces. The black king has access to d5 and d3, which are regarded as unprovided flights because White has no set mates available if the king moves to these squares. The question is thus how to deal with these flight-taking moves. The try 1.Rc6? (waiting) provides for 1…Kd5 with 2.Qf3, and 1…Kd3 with 2.Qf5, but is defeated by 1…d3! A second try, 1.Sba3? (waiting), reverses the two queen mates against the same defences: 1…Kd5 2.Qf5 and 1…Kd3 2.Qf3, but 1…d3! again refutes. Such a reversal of white mates across two phases constitutes a reciprocal change. This additional effect is cleverly brought about by the way in which the try-pieces guard and unguard different squares along the c-file. Lastly, the key 1.Qf2! (waiting) produces a completely different pair of mates, 1…Kd5 2.Qxd4 and 1…Kd3 2.Qe2, and also prepares for 1…d3 with 2.Sc3.
75. Valentin Lukianov
64 1981, 2nd Prize
Mate in 2
The excellent play of 75 revolves around two prominent captures by Black’s d5-pawn. 1.axb3? covers c4 and threatens 2.Qe3, and either black pawn capture would defend by creating a flight on d5: 1…dxc4 2.Qxc4 and 1…dxe4 2.Qd1; but the pinning 1…Ra2! defeats the try. 1.Kf3? covers e4 and threatens 2.Be3, and now 1…dxc4 Qd1 and 1…dxe4+ 2.Qxe4; but another pinning defence refutes, 1…Rf7! Correct is 1.e6!, which threatens 2.Be5 and significantly enables the white rook to observe d5. The resulting variations are 1…dxc4 2.Qe3 and 1…dxe4 2.Be3. Notice an interesting paradox that further connects the virtual and actual play. Previously, the try 1.axb3? carried the threat of 2.Qe3, against which 1…dxc4 was a defence. But after the key, this 1…dxc4 move ironically provokes the very mate, 2.Qe3, it stopped before. Similarly, the try 1.Kf3? threatened a mate, 2.Be3, that was prevented by 1…dxe4+, but after the key, Black’s 1…dxe4 actually induces that same mate, 2.Be3.
76. Horacio Musante
British Chess Magazine 1956, 1st Prize
Mate in 2
Problem 76 involves one more phase than the previous examples, generating a 4x2 Zagoruiko. Black’s main defences are 1…Se2 and 1…Sh3, both of which cause a weakness by cutting off a black rook’s line. White exploits each of these interferences in four different ways. The set play is 1…Se2 2.Be6 and 1…Sh3 2.Bxh7. When White moves the knight away from f4 to threaten 2.Rf4, the white bishop is left alone to control e6, so it can no longer give the set mates. The try 1.Se6? obstructs the black pawn and attacks g5, enabling 1…Se2 2.Ra5 and 1…Sh3 2.Qxh7, but Black refutes by 1…Rxe6! Another try 1.Sg2? changes the play again, to 1…Se2 2.S2e3 and 1…Sh3 2.Sh4, and is answered by 1…Rxg2! The solution is 1.Sd3!, which observes e5 and frees the other knight to mate, 1…Se2 2.Se3 and 1…Sh3 2.Sh6. There are two by-play variations, 1…Re4 2.fxe4 and 1…e5 2.Qxf6.
77. Gerhard Maleika
Echecs Francais 1981, 1st Prize
Mate in 2
Problem 77 achieves a complex 3x3 Zagoruiko that incorporates three thematic defences, but the variations follow a clear logic. Two tries and the key are made by the b7-rook, whose opening of the bishop line sets up a threat, 2.Qxd5. Each of the three defences, 1…Bd4, 1…Raxa8, and 1…Rhxa8, leads to three changed mates. Curiously some of these mating moves recur against different black defences, so that instead of a total of nine different mates, only six mates transpire – this idea is called a reduced Zagoruiko. The first try 1.Rb4? supports the queen’s guard on d4: 1…Bd4 2.Qxd4, 1…Raxa8 2.Sd3, and 1…Rhxa8 2.Qh5, but 1…d4! refutes. The second try 1.Rh7? shuts off the rook on h8: 1…Bd4 2.Qh5, 1…Raxa8 2.g4, and 1…Rhxa8 2.Rh5, but 1…Rd3! refutes. The key 1.Rb3! shuts off the other black rook: 1…Bd4 2.Sd3, 1…Raxa8 2.Re3, and 1…Rhxa8 2.g4. (Also, 1…d4 2.Sd3.)
78. Michel Caillaud
British Chess Problem Society, Kingston 1999, Prize
Mate in 2
Have a go at solving 78 which has, in addition to set play, a try phase that is attractively analogous to the actual play.
Set play: 1…Sd-any 2.Qxf4, 1…Se-any 2.Qxf5, (and 1…Kxe5 2.Re6). Try: 1.Qg1? (waiting), 1…Sd-any 2.Qxe3, 1…Se-any 2.Qd4, but answered by 1…Sc2! Key: 1.Qd8! (waiting), 1…Sd-any 2.Qd4, 1…Se-any 2.Qxd5.