Norman Macleod Award winner and cyclic shift

The Norman Macleod Award, organised by the British Chess Problem Society, is bestowed on the most striking and original problem of any genre published in The Problemist over a two-year period. Given its emphasis on novelty, perhaps it’s not surprising that the Award had never been won by any two-movers, the most highly investigated of all genres. However, in the recently announced Award for the 2014-15 period, the Slovakian Grandmaster Peter Gvozdjak has managed to break the trend, by gaining first place with a brilliant two-mover. His problem realises for the first time a theme described as “fourfold cyclic shift in threat form” – a complex type of changed play. Before analysing it, though, I should provide an example of a two-mover showing the more standard form of cyclic shift.

A cyclic shift of mates is a kind of extension of the reciprocal change scheme. The latter involves set or try play where the defences 1…a and 1…b are answered by 2.A and 2.B respectively, but after the key, the white moves are switched: 1…a 2.B and 1…b 2.A (example: No.10). The two elements of play that get exchanged here – a pair of white mates – are increased to three or more elements in a cyclic shift to generate this “circular” pattern: 1…a 2.A, 1…b 2.B, 1…c 2.C in the set or try play, becoming 1…a 2.B, 1…b 2.C, 1…c 2.A in the actual play. This difficult idea, also called the Lacny theme, is accomplished very economically in the problem above. The try 1.Rh4? (waiting) prepares to attack f4 if Black moves the knight and also to pin the piece if the king takes the flight: 1…S~ [a] 2.Sh7 [A], 1…Kf4 [b] 2.Be3 [B], 1…B~ [c] 2.Qxg4 [C], but 1…Be6! defeats the try. The key 1.Rf7! (waiting) again aims for f4 but exploits the black bishop’s position instead, and the rook also covers f6 while unguarding h6. Now we see three changed variations where the same mates reappear but are shifted to other defences: 1…S~ [a] 2.Be3 [B], 1…Kf4 [b] 2.Qxg4 [C], 1…B~ [c] 2.Sh7 [A].

The Award winner demonstrates a fourfold cyclic shift as it contains a similar pattern but with four thematic defences and mates. Such a scheme is rarer but not new; what’s new is the form of that cyclic play, viz. the four mating moves are multiple threats, which are then separated or uniquely forced by the four defences. In the initial position, the g2-bishop and a5-rook are both controlling a potential flight on d5. Each of these line-pieces is cut off in turn by the d4-knight with the try 1.Sf3? and key 1.Sb5! Both knight moves create these four threats: 2.Qg8/Sxb2/Qd4/Qc3. The four thematic defences all take place on f3 and b5 – the same squares visited by the white knight – so that Black either (1) closes the remaining white line of guard to d5 or (2) captures the knight and removes its control of d4. All of these strategic effects – and more! – are designed to make each black defence foil exactly three of the four threats while leaving the fourth viable. Thus the try 1.Sf3? gives 1…Sb5 [a] 2.Qg8 [A], 1…Qxf3 [b] 2.Sxb2 [B], 1…Rb5 [c] 2.Qd4 [C], 1…Sxf3 [d] 2.Qc3 [D], but 1…Rxd1! refutes. Among the many dual avoidance effects, note for instance how 1…Sxf3 pins the d1-knight and prevents 2.Sxb2. After the key 1.Sb5!, every defence remarkably stops a new triplet of threats to bring about these cyclic changes: 1…Sxb5 [a] 2.Sxb2 [B], 1…Qf3 [b] 2.Qd4 [C], 1…Rxb5 [c] 2.Qc3 [D], 1…Sf3 [d] 2.Qg8 [A]. An amazing fusion of cyclic shift, Fleck theme (separation of threats), and dual avoidance, this two-mover really pushes the envelope!