Novotny

The Novotny is a device found in chess problems. A white piece is sacrificed on a square where it could be taken by two different black pieces - whichever black piece makes the capture, it interferes with the other. It is essentially a Grimshaw brought about by a white sacrifice on the critical square.

This pattern could conceivably arise as part of a combination in an actual game, but it is extremely rare, and would probably not be called a "Novotny" if it happened--use of the term Novotny is essentially limited to the context of chess problems.

The device can be understood by reference to the problem to the right, a mate in 2 (white moves first, and must checkmate black in two moves against any defence). The key (first move of the solution; see chess problem terminology) 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.

The problem to the right is very well known. It contains no less 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 is followed by a white Novotny on move two:

• 1...Bb6 threatens 2...Ba5, interfering with the path of the white rook to a3. White counters with a Novotny interence: 2.Rd5. This interferes with the black rook on h5 and the bishop on a8, and so threatens 3.Nb5# and 3.Ne4#. Black can prevent one by capturing on d5, but not both, because the capturing piece interferes with the other (so 2...Rxd5 3.Ne4#; or 2...Bxd5 3.Nb5#).
• 1...Rbxb5 threatens 2...Ra5 stopping the threat. White can now play 2.Qd5 with the same interferences and threats as follow 1...Bb6.
• 1...Bc5 defends a3, stopping white's threat. White counters with 2.Rb7, interfering with the bishop on a8 and the rook on b8 and leading to the same threats and comparable continuations as follow 1...Bb6 (additionally, 2...Bxd6 allows 3.Bxd4#).
• 1...Bb7 threatens to capture the white rook which would give mate. White can now play 2.Rc5 interfering with the bishop on a7 and the rook on h5, and so threatening 3.Nb5# and 3.Bxd4#. As before, a caputre on c5 stops one of the threats, but not both.
• 1...Bd5 threatens 2...Bc4, after which black could meet white's threatened 3.Ra3 with 3...Bb3. White instead plays 2.Rbb6 with the same threats and variations as follow 1...Bb7.
• 1...Rhxb5 threatens 2...Ra5, stopping the threat. White instead plays 2.Rb6 with the same threats and variations as follow 1...Bb7.

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 c3. This allows 2.Ra3+ Nb3 3.Rb3#.)

Many problems include a Novotny as part of some larger scheme. The problem to the right, 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.Nxd2 but allows 2.Ne5#. 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 (pinss 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)