Abdel Irada: <The paradox of the minor pieces<<<>>>>
Although there are few pieces on the board, this puzzle is far, far tougher than many we've seen lately. For this paradox we can thank the nature of minor piece endings with advanced passed pawns: Suddenly, material value takes on entirely new, and often apparently enigmatic, meanings.
(This is reminiscent of a blitz game I played, years ago, against an extremely tough Afghani named Farouq, who although his rating was only in the 2100s was very quick and solid, fought like a lion, and was consequently difficult to beat in fast games.
Both players had two knights, a bishop and some advanced passed pawns on the queenside, with the kings somewhat out of play on the other wing. I had an extra pawn, but Farouq's passed c-pawn was more advanced than my corresponding b-pawn.
On autopilot, I attacked his bishop with one of my knights, threatening to take it for nothing with check. But Farouq brilliantly ignored this empty threat and pushed his c-pawn, realizing that if I wasted time picking up the bishop, I wouldn't get back in time to stop the pawn. Eventually, I was forced to sac the knight to stop the pawn.
But turn about is fair play, and now it was my turn. I pushed my own b-pawn, and finally Farouq, in turn, had to sac a piece to stop it. This left us in a far simpler ending, and I was still a pawn ahead and went on to win.)
Now back to the puzzle:
My first inclination, having seen that 47. a7 goes nowhere after Black screws his knight into a8, was to pin the knight with 47. Ba5, and it appears that this works, although in seemingly mysterious ways:
Now White threatens to win a piece, and will do so on the immediate 47. ...Na8?, forcing the king to come back to defend.
(Of course, 47. ...Nxd7? is out of the question, for after 48. a7, Black can't stop the pawn.)
Again, Black has only one defense. Taking the knight with either king or knight loses, the latter to an immediate pawn push, the former to an exchange on b6 followed by a pawn push. Stopping the pawn is more important than trying to win a piece, so:
This does not lose a piece because White's knight is also hanging.
<49. Bxd8, Kxd7
The point: Although the pawn is blocked and material is even, the black knight is corraled by the bishop long enough to secure a win on the kingside.
Black needs to keep the king near the pawn. If he goes to e6 to hold his kingside pawns, the white king penetrates on the queenside and traps the knight, freeing the bishop to stop counterplay while the trapped knight is picked off and the a-pawn advanced.
<51. Ke4, Kb7<>>
To advance the pawns at this stage only weakens them, easing White's task.
<52. Kf5, Kxa7
53. e6, fxe6†
54. Kxe6, Nb6
55. Kf7 <>>
I'd have to spend some time proving the win, but this appears stronger than exchanging on b6. The king-and-pawn ending looks like a draw after 55. Bxb6†, Kxb6; 56. Kf7, g5!; 57. Kf6, Kc6; 58. Kxg5, Kd7, and Black's king reaches c7 in time to achieve one of the known king-vs.-rook's-pawn draws, in which White will ultimately have the unpalatable choice of stalemating Black or being stalemated himself.
With the minor pieces on, however, the advantages of the long-range bishop against the short-stepping knight combined with White's better king placement will eventually lead to a win.