Danny Sparkes and Norbert Friedrich.
Danny Sparkes recently took us through the technique here, and had some fun at the expense of a range of computers and computer programmes who seem generally clueless about t. I don't have his notes but I do have tucked away some similar notes by Norbert Friedrich, who also has a mild dig at computer technique, and whose notes I have expanded on a little below. (If you have ChessBase 6.0 or above, the database will show some helpful extra detail of the patterns.)
Why bother?
(1) You might have to do it, and under pressure. Susan Lalic was surprised by Galliamova recently, who headed for this endgame as a reasonable drawing attempt. Susan made the mate - in 45!
(2) It also illustrates how to co-ordinate three slightly awkward pieces - perhaps you may never have to prove the mate, but you will have to co-ordinate the activity of your minor pieces, and this is a suitable arena in which to rehearse.
(658) The basic technique [Norbert Friedrich]
DRAWING A "W": To win KBN-K you first have to force the king to the 8th rank. If the king escapes to his safe corner then, "drawing an W" is a useful help to remember. The knight moves like a "W" (c7-d5-e7-f5-g7), the bishop does not allow Black's escape to the safe corner and the White king steps towards the winning corner on the 6th rank. Finding the mate then should not create problems anymore. 1.Nc7+ Kb8 2.Bc5 Kc8 3.Ba7 Kd8 4.Nd5 Ke8 Offers more resistance than Kc8
[4...Kc8 5.Ne7+ Kd8 6.Kd6 Ke8 7.Ke6 Kf8 (7...Kd8 8.Bb6+ Ke8 9.Ba5 Kf8 10.Nf5 Ke8 11.Ng7+ Kf8 12.Kf6 Kg8 13.Kg6 Kf8 14.Bb4+ Kg8 15.Bc5 Kh8 Now you must play a check to g8 with the Knight, but not from f6! 16.Nf5 Kg8 17.Nh6+ Kh8 18.Bd4#) 8.Nf5 Ke8 9.Bb6 Kf8 10.Bc7 Ke8 11.Ng7+ Kf8 12.Kf6 Kg8 13.Kg6 Kf8 14.Bd6+ Kg8 15.Nf5 Kh8 16.Be7 Kg8 17.Nh6+ Kh8 18.Bf6#]
5.Kd6 Grit you teeth and allow the King to come forward two squares... 5...Kf7 6.Ne7 Stops the King coming to g6. 6...Kf6
[6...Kg7 7.Be3]
7.Be3!
The second detail to remember. The King covers the red squares (ChessBase 6 format), the Knight covers the green squares, and the Bishop covers the yellow squares, and the 'net' effect is a box from which the Black King can only escape backwards. Neat, eh? 7...Kf7 8.Bd4 The net effect again. 8...Ke8 9.Ke6 Kd8 10.Bb6+ Again, the Bishop and Knight cooperate to block off all the escape squares on the c-file.. 10...Ke8 11.Nf5 Kf8 12.Bc7 Ke8 13.Ng7+ Kf8 14.Kf6 Kg8 15.Kg6 Kf8 16.Bd6+ Kg8
Now it's mate in four: we must play check to g8, but not from f6. 17.Nf5 Kh8 18.Be7 A tempo move. 18...Kg8 19.Nh6+ Kh8 20.Bf6# 1–0
(659) Endgame Data Bases [Norbert Friedrich]
Any endgame database (Check those by Ken Thompson) will tell you that there might be faster wins or better defenses. Its mysterious move suggestions might be of scientific interest but are IMO hardly of a practical value: The following was recently posted in rec.games.chess.analysis by Steven Edwards. Note that the bishop is on e3 and the knight on d5, though that should not create a difference. Evaluation: Mate in 20 1.Bb6 Bc5 Bd4 Bf2 Bf4 Bg1 Nc7+
[After playing the following moves: 1.Nc7+ Kb8 2.Bb6 Kc8 3.Ba7 Kd8 4.Nd5 Kc8 ... Evaluation: Mate in 13 5.Ne7+ Kd8 6.Kd6 Ke8 7.Ke6 Kd8 Kf8 8.Bb6+ Ke8 9.Nf5 Kf8 10.Bc5+ Bd4 Bd8 Be3 Bf2 (10.Be3 Ke8 11.Bg5 Kf8 12.Be7+ Kg8 13.Kf6 Kh7 14.Kf7 Kh8 15.Kg6 Kg8 16.Nh6+ Kh8 17.Bf6#) 10...Ke8
If letting the Black King off the back rank makes you nervous, you will have to see the mate in 6, which starts by threatening mate in one, by shielding the line of the Bishop. 11.Nd6+ Kf8 (11...Kd8 12.Bb6#) 12.Kf6 Kg8 13.Nf5 discovering an attack on the square just vacated. 13...Kh7 14.Kf7 Kh8 15.Kg6 Kg8 16.Nh6+ Kh8 17.Bd4#]
1...Kb8 2.Nc7 Kc8 3.Ba7 Kd8 4.Nd5 Ke8 5.Bd4 Kd6 5...Kd8 Kf7 6.Be5 Kc8 7.Nb6+ Ne7+ 7...Kd8 8.Bf6+ Kd6 8...Ke8 9.Kd6 Kf7 10.Nd5 Kf8 Kg6 11.Ke6 Ke8 12.Bg5 Bh4 Nc7+ Ne3 12...Kf8 13.Be7+ Kg7 14.Nf4 Kg8 Kh7 15.Kf6 Kh7 Kh8 16.Bf8 Kg8 Kh8
A different mate in four. 17.Ne6 Kh7 Kh8 18.Kf7 Kh8 19.Bg7+ Kh7 20.Nf8# Ng5# Line
(661) Fine No.4/No.5 [RF]
The White pieces are in their worst possible positions. Mate can be achieved only at a8 or h1.As White you have a three-stage plan:(1) drive the King to the edge.(2) drive the King to a corner: it will (or should) head for a1/h8(3) drive the King across to the other corner. 1...Kc6
[1...Kc4 2.Bf7+]
2.Nb3 Kd6
[2...Kd5 3.Kb5 Kd6 4.Kc4 Ke5 5.Nc5 Kf5 6.Kd5 Kg5 7.Bf3 Kf5 8.Ne6 Kf6 9.Be4 Ke7 10.Ke5 Kf7 11.Nf4 Kg7 12.Bd5 Kh7 13.Kf6 Kh8 14.Ng6+ Kh7 15.Be6]
3.Kb5 Kd5 4.Bf7+ Ke5
[4...Kd6 5.Bc4 Ke5 6.Kc5 Ke4 7.Kd6 Kf5 8.Bd3+ Kf6 9.Nd2 Kf7 10.Nc4 Kf6 11.Ne5 Kg7 12.Ke7 Kh8 13.Kf6 Kg8 14.Nf7]
5.Kc5 Kf6 6.Bc4 Ke5 7.Nd2 Kf4 8.Kd6 Kf5
[8...Ke3 9.Nb3 Kf4 10.Bd3 Kg5 11.Ke5 Kh6 12.Kf6 Kh5 13.Bf5 Kh4 14.Kg6 Kg3 15.Kg5 Kf3 16.Bc2 Ke3 17.Kg4 Ke2 18.Kf4 Kf2 19.Bd1 Ke1 20.Bf3 Kf2 21.Nd4]
9.Bd3+ Kf6 10.Nf3 Kf7 11.Ke5! Kg7
[11...Ke7 12.Bc4]
12.Ng5
[While we are going through, watch how the Knight moves!]
12...Kg8! 13.Kf6 Kf8 14.Nf7 Kg8
No.5Black is near the 'safe' corner, and we need to get him to a mating corner. The way to do this was first shown by Philidor, and is to be found in the books by Fine and Averbakh. 15.Bf5 Kf8 16.Bh7 Ke8 17.Ne5 Kd8
[17...Kf8? 18.Nd7+ Ke8 19.Ke6 Kd8 20.Kd6 Ke8 21.Bg6+ Kd8 22.Nc5 Kc8 23.Bd3! Kd8 24.Bb5! Kc8 25.Bd7+ Kb8 26.Kc6 Ka7 27.Kc7 Ka8 28.Kb6 Kb8 29.Na6+ Ka8 30.Bc6#]
18.Ke6 Kc7 19.Nd7! This is the bit you need to understand: it looks like the King has got out, but it hasn't. 19...Kc6?! This natural move gets mated more quickly. There are a couple of important patterns to remember:
[19...Kb7 20.Bd3! Kc6 The 'net effect' box again. 21.Ba6 Kc7 22.Bb5 and the wall. 22...Kd8 Okay, last trick. The Knight goes to d5 to further restrict the King. 23.Nb6 Kc7 24.Nd5+ Kd8 25.Kd6 Kc8 26.Ke7 Kb7 27.Kd7 Kb8 28.Ba6 Ka7 29.Bc8 Kb8 30.Ne7 Ka7 (30...Ka8 31.Kc7 Ka7 32.Nc6+ Ka8 33.Bb7#) 31.Kc7 Ka8 32.Bb7+ Ka7 33.Nc6#]
20.Bd3! The King is in a little box. 20...Kb7
[20...Kc7 21.Bb5! The King's escape is walled off. 21...Kc8 22.Kd6 Kd8 23.Nc5 Kc8 24.Bd7+ Kb8 25.Kc6 Ka7 26.Kc7 Ka8 mate in three 27.Kb6 Kb8 28.Na6+ Ka8 29.Bc6#]
21.Kd6 Kc8 22.Nc5 Kb8
[22...Kd8 23.Bb5]
23.Kc6 This is not the fastest but is easier to remember and more artistic.
[23.Kd7 is Fine's slightly quicker method 23...Ka7 24.Kc7 Ka8 25.Kb6 Kb8 mate in three 26.Ba6 Ka8 27.Bb7+ Kb8 28.Na6#]
23...Kc8 Can you guess White's next Knight move? 24.Nb7 This is why I say it's easier to remember and prettier! 24...Kb8 25.Kb6 Kc8 26.Bf5+ Kb8
Now its mate in four. 27.Nc5 Ka8 28.Bd7 A tempo move. 28...Kb8 29.Na6+ Ka8 30.Bc6# 1–0