Here is How Chess Engines DON’T Think!
Actually, they don’t think, they are just number crunchers
Our positionally tactical1 puzzle for the Dec. 1 week is Donner-Petrosian from the 1955 Gothenburg Interzonal.
Below is position after 30…b5. Black actively plays on the Q-side to make advantage of his pawn majority there. White has to find the right answer to it. In the game Donner played 31.Rxa5, suggested also by my aged digital moron (its name is Fritz 6; it evaluates the position as equal).
As we know, chess masters build up position until it is superior. We also know that only superior positions can yield tactical opportunities (in the form of big tactics that decides the outcome of the game instantly) – that’s why they are superior.
But how chess masters build and improve an equal position in a seemingly slow fashion, gradually? How they make a position that is difficult to play, where they may be prone to making mistakes, to one which is clearly a draw? The latter is exactly what the Donner-Petrosian position below can teach us, by smart use of small tactics — positionally tactical! But not Fritz, or Hudini, or any other metal-head chess engine. They are tactical monsters, but they are also positionally retarded, so to speak. In spite of their enormous speed, they are still unable to see what a chess master can see in no time without any calculation to make the right decision! Hey, tactics without calculation thanks to positional feeling! Something tactical freaks will never be able to do!
So far, we have seen examples of little tactics that has used threats1. A combination typically offers a sacrifice. Both secure some positional advantage tipping the scales in our favor. The so called petite combinaison was Capablanca’s favorite weapon. It would normally bring him a small positional gain, or a slight improvement. The combination Donner missed was pretty complex and hard to see so we don’t put any blame on him.
1. d4 Nf6 2. c4 c5 3. d5 e6 4. Nc3 exd5 5. cxd5 d6 6. Nf3 g6 7. Nd2 Nbd7 8. g3 Bg7 9. Bg2 O-O 10. O-O Qe7 11. h3 b6 12. a4 Ba6 13. Re1 Ne8 14. Nb5 Bxb5 15. axb5 Nc7 16. Qb3 Nf6 17. Nb1!
Well played! White defends his only weakness, the b5-pawn, by transferring his knight to c3.
Black is now faced with a difficult task of choosing the right plan. White has an advantage in the center. He is going, in time, to move his e- and f-pawns preparing for the e4-e5 breakthrough. There is no foundations for any active play on the K-side. So the only option for Black is to play on the opposite side.
Playing 17…a6 right away gives advantage to White: 18.bxa6 Rxa6 19.Rxa6 Nxa6 20.Qxb6 Nb4 21.Bf4, or 18…Nxa6 19.Qxb6 Nb4 (19…Rfb8 20.Qc6 Nb4 21.Qxa8) 20.Rxa8 Rxa8 21.Bf4.
Looks better for Black 17…a6 18.bxa6 b5 but then White plays 19.a7 and it is not clear how Black can retake the a-pawn. If, for instance 19…b4 with the idea …Nb5, then White has 20.Ra5.
The right move after 17…a6 18.bxa6 is 18…Rfb8! which secures the recapture of the a-pawn and b6-b5.
If White after 17…a6 plays 18.Nc3, the best continuation for Black is 18…axb5 19.Rxa8 Rxa8 20.Nxb5 Ra5 21.Nxc7 Qxc7 22.Bd2 c4 with better perspectives than in the game.
If (in place of 18…axb5) Black plays 18…c4, then 19.Qb4 (19.Qxc4? axb5) gives hard time to Black.
18. Nc3 a6 19. Be3 axb5 20. Nxb5 Nxb5 21. Qxb5 Nd7 22. Bd2
White is transferring the bishop to c3 in order to trade the strong g7-counterpart; at the same time, White prevents 22…Ra5.
22…h5 23. Bc3 Qd8 24. f4 h4 25. g4 Bxc3 26. bxc3 Ra5 27. Qc6 Nf8 28. e4 Rc8 29. Qb7 Rb8 30. Qc6 b5
When Black was calculating the consequences of his move 30, he didn’t like 31.e5! Rb6 (the queen is trapped, but) 32.Rxa5! Rxc6 33.dxc6 Qxa5 34.exd6 Qxc3 and White has very powerful pawns d6 and c6.
This is exactly positional gain that our petite combinaison yielded to White. An instant draw, as compared to unclear game where he made a mistake at move 32.
Now 35.Re4 is parried with 35…f5 36.d7 fxe5 37.d8Q Qe1+ 38.Bf1 e3 39.Qd3 c4.
Stronger is 35.Rd1 Qb3 and with 36.Rd1 White forces draw which would be the logical end of a tense game.
31…Qxa5 32. Re3? considerably stronger is 32.Qxd6
32…b4 33. Qxd6
If 33.cxb4 cxb4 34.Qxd6 Qa7 35.Kh2 b3 36.Re1 b2 37.Rb1 Rb3 followed by 38…Qf2.
Or 35.Kh1 b3 36.Re1 b2 37.Rb1 Rc8.
The weak position of the white king and the b-passer decide the game.
33…Rb6 34. Qc7 bxc3 35. Re1 c2 36. Rf1 Qb4
Decisive was also 36…Qb5 with the 37…Qxf1+ threat.
37. Kh2 Rb7 38. Qc8 Rd7 39. Qa8 Qd2 40. Qa3 c4 41. Qa1 Rb7 0-1
1. Find out more about our positionally tacticals puzzles and why they are so important to play chess well in Want to improve your positional chess? Tal can help!