Lacny
Encyclopedia
The Lacny or Lacny cycle is a chess problem
theme named after Ľudovít Lačný
, 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.
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:
The key to the solution is 1.Nd2 (threatening 2.Nf1#), after which the mates are changed thus:
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 and E respectively in one phase and B, C, D, E and A respectively in another. The cycle can also be extended over three phases to make a complete Lacny cycle; here, the defences a, b and c are answered by the mates A, B and C respectively in one phase; by B, C and A respectively in another; and by C, A and B respectively in a third. This is considerably harder to achieve than the "simple" Lacny, and there are relatively few examples.
In the related threat Lacny, short-cut Lacny or Dombro-Lacny, in one phase A is threatened, and defence b leads to mate B while defence c leads to mate C; in another phase B is threatened and defence b leads to mate C while defence c leads to mate A. Once, problems following this scheme were also called Lacnys, but now a distinction tends to be drawn between the two (Peter Gvozdjak in Cyclone suggests this scheme should be called the Shedey cycle after its originator, Sergei Shedey). There are a number of other themes featuring cyclic play in different phases, including the Kiss and Djurasevic cycles.
Chess problem
A chess problem, also called a chess composition, is a puzzle set by somebody using chess pieces on a chess board, that presents the solver with a particular task to be achieved. For instance, a position might be given with the instruction that White is to move first, and checkmate Black in two...
theme named after Ľudovít Lačný
Ludovít Lacný
Ľudovít Lačný is a Slovak chess problem composer and judge.He was born in Banská Štiavnica and studied mathematics, working as a teacher, and as a computer programmer....
, 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
Phase of play
Phases of play are parts of a chess problem which happen, as it were, concurrently rather than consecutively.Each problem has at least one phase: the post-key play or actual play; that is, the play after the key...
, 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.
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 and E respectively in one phase and B, C, D, E and A respectively in another. The cycle can also be extended over three phases to make a complete Lacny cycle; here, the defences a, b and c are answered by the mates A, B and C respectively in one phase; by B, C and A respectively in another; and by C, A and B respectively in a third. This is considerably harder to achieve than the "simple" Lacny, and there are relatively few examples.
In the related threat Lacny, short-cut Lacny or Dombro-Lacny, in one phase A is threatened, and defence b leads to mate B while defence c leads to mate C; in another phase B is threatened and defence b leads to mate C while defence c leads to mate A. Once, problems following this scheme were also called Lacnys, but now a distinction tends to be drawn between the two (Peter Gvozdjak in Cyclone suggests this scheme should be called the Shedey cycle after its originator, Sergei Shedey). There are a number of other themes featuring cyclic play in different phases, including the Kiss and Djurasevic cycles.
Further reading
- Peter Gvozdjak, Cyclone (Bratislava, 2000) - includes 626 Lacny cycles and 42 complete Lacnys