{"document_url": "https://en.wikipedia.org/wiki/Novotny_(chess)"}
The Novotny (also often spelled as Nowotny, even in non-German sources) is a device found in chess problems named after a problem from 1854 by Antonín Novotný, though the first example was composed by Henry Turton in 1851. A piece is sacrificed on a square where it could be taken by two different opposing pieces, but whichever makes the capture, it interferes with the other. It is essentially a Grimshaw brought about by a sacrifice on the critical square.

This pattern can arise as part of a combination in an actual game, but it is extremely rare (see games below). Most chess players would not use the term "Novotny" to describe such a move, since that term is almost exclusively used in the context of chess problems.

Examples

Basic
White to play and mate in two.

The device can be understood by reference to the problem shown here, a mate in two moves (white moves first, and must checkmate black in two moves against any defence). The key (first move of the solution; see Glossary of chess problems) is 1.Nb2 (see algebraic notation). This interferes with black's rook and bishop, and whichever of those pieces takes the knight, it will interfere with the other—this is the Novotny idea at its most basic. So, if black plays 1...Bxb2, this interferes with his rook and allows 2.Qf2#, while if he plays 1...Rxb2, it is the bishop that is interfered with, allowing 2.Qd4#.

Problemists would generally agree that a single Novotny with no other play, as in this example, makes for a relatively uninteresting problem. Usually, Novotnys are combined in problems with other ideas, or several Novotnys are shown in a single problem.

Multiple Novotnys

R. C. O. Matthews, British Chess Magazine, 1957
White to play and mate in three.

The problem as shown here is very well known. It contains no fewer than six separate Novotnys. It is by R. C. O. Matthews, was published in the British Chess Magazine in 1957 and won the Brian Harley Award. It is a mate in 3.

The key is 1.b4, threatening 2.Bxb1 and 3.Ra3#. Black has six thematic defences, each of which White meets with a Novotny on move two:

The solution, in short form, is thus: 1. b4

Four of White's Novotnys in these variations are executed by the rook on b5—only the rook will do in those variations, because the square it comes from, b5, must be vacated for the white knight to deliver mate. In the other two lines, that rook is captured, meaning it cannot execute the Novotny, but also meaning the square vacation is no longer necessary (the white knight can simply capture the black piece on b5). Therefore, another piece can make the Novotny interference in those lines. (There is one other non-thematic defence in the problem: 1...Nd2, threatening a nuisance check on b3. This allows 2.Ra3+ Nb3+ 3.Rxb3#.)

As part of a larger scheme

Milan Vukcevich, Schach-Echo, 1976
White to play and mate in two.

Many problems include a Novotny as part of some larger scheme. The problem here, by Milan Vukcevich, published in Schach-Echo in 1976, includes a Novotny as just one part of a more complex problem. It is a mate in 2. The key is 1.Qd6, which is a Novotny interference with the black rook and bishop on b8, so threatening 2.Ne5# and 2.Nxd2#. After the capture of the queen by the rook or bishop, the other black piece is still interfered with by the capturing unit; so 1...Rxd6 rules out 2.Nxd2 but still allows 2.Ne5#, while 1...Bxd6 rules out 2.Ne5 but allows 2.Nxd2#. Just as these Novotny lines work as a pair, so the other black defences work in pairs:

1...Rxa7 (removes white guard of e3) 2.Qd3#
1...Bxa7 (removes white guard of e3) 2.Qf4#
1...e5 (pins the knight that gives the mate in the Novotny lines) 2.Qf6#
1...Bd5 (pins the knight) 2.Qxa3# (not otherwise possible because of 2...Rd3)

The Novotny theme in practical play
Macdonald–Burn, offhand game, Liverpool 1910, position after White's 33rd move.

The Novotny theme occurs extremely rarely in actual play. The strong English master Amos Burn produced such an example in an offhand game in 1910 (see diagram). In a seemingly desperate position, with his king apparently about to fall to a powerful attack by White's pieces, Burn played 33...Qg4!! The point is that if the bishop or pawn takes the queen, the white rook's pin on the black bishop is lifted, allowing 34...Bxd2; if the rook takes the queen, the white bishop no longer protects f3, so Black can play 34...Nf3+ and 35...Nxd2. Finally, if 34.Qxg5+, Qxg5 35.Rxg5+ Kh6 wins a piece. Burn won in 15 more moves.
Rubtsova-Belova, USSR 1945, position after 1.Rf4-g4?

In this position, from Rubtsova-Belova, USSR 1945, White has just played the attractive-looking 1.Rf4-g4? Black cannot capture the rook (1...Qxg4? 2.Bxg4; 1...fxg4?? 2.Qxg5), and White would win a piece after 1...Qf6? 2.Rxg3. However, Black responded with a decisive Novotny, 1...Ne2+! This enables Black to win the rook after 2.Rxe2 Qxg4; 2.Bxe2 Qxe3+ and 3...fxg4; or 2.Kf1 Qxg4. Black won.
E. Berg–J. Zezulkin, Rowy 2000, position after Black's 39th move.

The Novotny theme could also have occurred in actual play in E. Berg-J. Zezulkin, Rowy 2000. From this diagram, White could have won with 40.Nf6!! (instead of 40.Qe6?, leading to an eventual draw). After 40.Nf6!!, White would threaten the two thematical mates 41.Qg7# and 41.Qf8# and in addition 41.Rg8# and 41.Qxh7#. Now 40...Bxf6 would block Black's rook, allowing 41.Qf8#, while 40...Rxf6 would block Black's bishop, allowing 41.Qg7#. After 40...Qxh6 which parries both thematical threats White has 41.Rg8#.
David Navara vs Anna Dergatschova-Daus, Ordix Open (2007), position after Black's 35th move.

The Novotny theme was played in David Navara vs Anna Dergatschova-Daus, Ordix Open (2007), Mainz, 2007. If White could check on the a2–g8 diagonal, it would force mate quickly. But the R guards e6, and the B guards d5. So 36. Rc6!! intersects both lines: 36... Rxc6 37.Qd5+ Re6 38.Qxe6#, or 36... Bxc6 37.Qe6#; and if 36... Qxc6 then 37. e8=Q+ Qxe8 38. Qxe8#