Lacny

The Lacny or Lacny cycle is a chess problem theme named after Ľudovít Lačný [ˈlatʂ.ni], the first person to demonstrate the idea in 1949. It is an example of lines of play being cyclically related: in one phase of play, the Black defences a, b and c are answered by the White mates A, B and C respectively; in another phase, those same defences a, b and c are answered by the White mates B, C and A respectively. Ľudovít Lačný, 1949 White to play and mate in two The theme can be understood by reference to the problem to the right: this is the first problem to demonstrate the idea, by Lacny himself (first prize at the Przepiorka Memorial, 1949); it has been much-reproduced. The set play is: 1...Nh2 [a] 2.Qd4# [A] 1...c1=Q [b] 2.Ng2# [B] 1...c3 [c] 2.Qe4# [C] The key to the solution is 1.Nd2 (threatening 2.Nf1#), after which the mates are changed thus: 1...Nh2 [a] 2.Ng2# [B] 1...c1=Q [b] 2.Qe4# [C] 1...c3 [c] 2.Qd4# [A] As well as in set play (as in this example) the theme can be shown in tries, more than one solution or twins. The scheme can be expanded to include more defences; in a fivefold Lacny, for example, the defences a, b, c, d and e are met with the mates A, B, C, D a