Knight v Bishop (part two)

White has just captured on d1 in Spanton (151) - Hass Ha'eri-Zadeh (-), Middlesex League 1989. Who stands better, and by how much?

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This is another ending arising from the Exchange Variation of the Spanish. The pawn-formation is slightly better than usual for Black in that White has doubled b pawns. But the really unusual feature of this position is that it is White who has the bishop, Black who has the knight. Stockfish12 reckons White is winning; Komodo11.01 gives White just a slight edge (+.64).

21...Ng7

This is the engines' choice. The problem with 21...Kf8? is that White wins a pawn with 22.Be5.

22.Bxg7?!

Although there are 14 pawns on the board, a factor normally favouring the knight, White probably has better winning chances in the minor-piece ending thanks to there being rival mobile pawn-majorities.

22...Kxg7

HH-Z offered a draw.

23.Ke2 Kf6 24.Ke3 c5 25.f4

The engines prefer - marginally, in Komodo11.01's case - 25.Kf4!?

25...Ke6 26.g4 h6

This comes to be Stockfish12's choice, although once the move is played on the board it does not like it. In general at this point, though, the engines keep changing their top selections.

27.h4!?

Gaining space with 27.e5 is also strong, and if 27...Kd5 then 28.c4+ Ke6 29.Ke4.

27...f6

At first the engines love 27...h5, but then find 28.f5+ Ke5 (28...gxf5 29.gxh5) 29.fxg6 fxg6 30.gxh5 gxh5, after which the black king will eventually have to retreat.

28.Kd3?

Winning is 28.f5+.

28...b5?!

Black seems to have a draw, at least, with the engines' 28...Kd6! The point is to be able to meet f5 with ...g5, keeping the kingside closed. Indeed after 29.f5? g5 Black is winning, eg 30.h5 Ke5 31.Ke3 b5 32.c3 a5 33.Kf3 b4 34.Ke3 bxc3 35.bxc3 c4! White should play 29.Ke3, hoping for 29...Ke6? 30.f5+, but Black has 29...Ke7! with an equal position.

29.Ke3!?

This may be good enough, but surer is the engines' 29.f5+! gxf5 30.exf5+, eg 30...Ke5 31.Ke3 a5 32.c4 b4 33.Kf3 c6 34.Ke3 Kd6 35.Kf4 etc.

29...Kd6 30.Kf3 Ke6?

This again allows the winning f5+. The engines reckon White's advantage is much smaller after 30...b4 or 30...Ke7.

31.g5? hxg5 32.hxg5 fxg5 33.fxg5 Ke5 34.Ke3 a5 35.Kf3?

And now Black is winning. Correct is 35.c3, eg 35...b4 36.c4 c6 37.Kf3, when neither side can make progress (certainly not 37...Kd4? 38.Kf4 with e5 to follow).

35...c4?

Winning is 35...b4 36.Ke3 c4! (36...c6 also wins) 37.Kf3 (37.bxc4 a4 etc) cxb3 38.cxb3 Kd4 39.Kf4 c5 40.e5 Kd5.

36.bxc4 bxc4 37.Ke3 a4 38.c3 Resigns??

The final position is dead-equal.