Movement-limitation patterns in pieces

Arrangement between two pieces (or more) can result in limitation of movement for one of the pieces, or both of them in mutual-movement limitation. That's well known. The typical example is the Bishop and Knight separated by two ranks or files (see Diagram below), where the Knight sees all of its movements stopped in the direction of the Bishop. As for the Queen, being on the adjacent square leads to the same result -- the limitation of the Knight's movements towards the Queen.

One less well known pattern is the one involving the Rook and Knight. Perhaps you know that a Rook and Knight on two adjacent squares on the same diagonal leads to the limitation of the Knight's movements in the specific direction of the Rook (i.e., it blocks two squares; see in the Diagram below and imagine the Knight one step closer to the Rook). But there is another important pattern: when the Rook and Knight have a square between them on the same diagonal. In that case, the Knight sees four of its available squares taken away, with devastating results when the Knight is on the side of the board. When in the corner, this is the way to trap the Knight with a Rook (see Diagram below).

I remember using this pattern during a middlegame, where my opponent's Knight was on the side of the board, and my using this pattern led to the trapping of the Knight (and eventually to its capture). You might also be interested in the game Karpov-Ftacnik, Olympiads 1988 (you can search on http://www.chesslive.de/), which involves a pawnless Rook vs Knight ending.

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The last pattern I will discuss here is of another kind. It shows the cooperation between two Knights separated by two ranks or files, given that they are on the same file or rank (see Diagram below). In that case, both dark- and light-squares in-between them are under their control, except for the squares directly aligned with the two Knights.

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In the game Harikrishna-Volokitin, 2005a, White could have used this pattern to win a pawn:

1. Bxf5! Bxf5 2. Rf4 Kg5 3. g3!!

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This move protects both the Rook and Knight, but most importantly now, whatever Black plays, White's next move is to take back the Bishop with the Rook and then throw the powerful Ne4+, winning back the material. A possible continuation is 4. ... Ne6 (attacking White's Rook and defending Black's own Rook) 5. Rxf5+ Rxf5 6. Ne4+ (see Diagram below).

And we see the pattern. Black needs to move his King, but due to the configuration of the Knights, it can't go anywhere to protect the Rook, and White ends up being a pawn-up in a two-knights-vs-two-knights ending.