SANDS: Exchange rate in chess fluctuates for rooks, minor pieces

Through centuries of theoretical investigation and practical results, the relative value of the pieces on the board has been pretty firmly established. If the pawn has a value of one, then the minor pieces (knights and bishops) are worth a little more than three pawns, the rook five, and the queen somewhere between 9.5 and 10. In many games with players of even moderate strength, a material edge of plus-one — a single pawn — is enough to produce a winning advantage.

But modern play is casting more and more doubt on the value of “the exchange” — winning your opponent’s rook in exchange for just a knight or a bishop. Especially in the early middlegame, it seems top players are anxious to give up the exchange for positional or attacking considerations, and often it’s the defender’s best strategy to give back the “extra” material as soon as possible.

Rising New York-born Italian GM Fabiano Caruana, who has rocketed into the world’s top 10 in recent months, gave a textbook example of how it’s done at the superstrong fifth Final Masters Tournament, an event that is split between Bilbao, Spain and Sao Paulo, Brazil. Against GM Sergey Karjakin, Caruana first outplayed his Russian opponent positionally, then uses a devastating exchange sac to bust open White’s game.

In a classic Ruy Lopez Closed battle, Karjakin’s efforts to hold on to his bishop pair end up ceding too much space to the Italian, who uses a neat maneuver to get his own bishops into the battle: 18. b3 Ba5! (an inspired idea — the liberated bishop will disrupt White’s plans from its perch on c3, while keeping a weather eye on e5, typically the most contested square in this opening) 19. Rab1 Bc3 20. Rec1 b4 21. a4 a5 22. Bd3 h6 23. Qd1 Ba6 24. Bc2?. This retreat is understandable, as White has won a ton of Ruy battles with the bishop patrolling the b1-h7 diagonal. But here it is Black’s bishop on a6 that will prove the more powerful piece.

With White’s attack going nowhere, Caruana proceeds to give up both rooks to strip White’s king of needed defenders, while his own bishop pair dominates the position: 26. g4 Nxe4! 27. Nxe4 Rxe4 28. Bxe4 Rxe4 29. Qc2 Qe7 30. Rg1 Rxe3! (the classic exchange sacrifice — the White bishop was the last piece holding the defense together) 31. fxe3 Qxe3, when the analysts at Chessvibes.com noted that even the computerlike defense 32. Rg3 Bd3 33. Re1 Bxe1 34. Nxe1 Qxg3+ 35. Kxg3 Bxc2 36. Nxc2 only manages to land White in a lost knight-and-pawn ending.

But Black invades anyway on the game’s 32. Rfb1 Be2! (declining to win back the exchange in favor of a decisive attack) 33. Qf5 Bd3 34. Qd7 Be5+ 35. Kh1 Be4 36. Qe8+ Nf8, and White can’t save the knight with 37. Kg2 because of the deadly 37. … Qe2+ 38. Rf2 Bxf3+ and wins; Karjakin resigned.

—-

It’s not just world-class grandmasters who have made the exchange sacrifice part of their arsenal. In a recent U.S. Chess League match, FM Ralph Zimmer of the Baltimore Kingfishers put away NM Joshua Colas of the Connecticut Dreadnoughts with another devastating rook-for-knight swap, one that left Black’s king defenseless against the ensuing assault.

The early dueling in this English Opening centers around Zimmer’s attempts as White to open up the position for his fianchettoed bishops, while Colas struggles to keep the center closed. White scores a breakthrough with 12. e3 Bd6 13. b4! dxe3 (b6? 14. exd4 exd4 15. Nxd4 loses the exchange for Black, and not in a good way) 14. fxe3 cxb4 15. d4 Rb8 16. c5, and White’s spatial advantage is well worth the lost pawn.

With the kingside files wide open, White’s priority becomes evicting the Black knights providing a last line of defense for their king: 20. Ng5 h6 21. Nge4 Bb5 (on 21. … Ng4, White can win material with the tricky 22. Qa4! Nxf2 23. cxd7 Nd3 24. dxc8=Q Bxc8 25. Rb1 Nxb2 26. Qb3! [Rxb2?? Qc1+] Be6 27. Qxb2) 22. Nxf6+ Nxf6 (see diagram) 23. Rxf6!, removing the last knight and crippling Black’s kingside. Colas is on the ropes after 23. … gxf6 24. Qf5 Bxc6 25. d5 Be5 (Bc5+ 26. Kh1 Bd7 27. Qxf6 and mate to follow), and it’s a bit of a shame that White doesn’t bookend his first exchange sacrifice here with a second one: 26. Rxe5! fxe5 27. Bxe5 Qe7 28. Ne4 f6 29. Bxf6 Rxf6 (Qf7 30. Qg4+) 30. Nxf6+ Kg7 31. Nh5+ Kg8 32. Qxc8+ and wins.

Nevertheless, Zimmer’s 26. Bxe5 fxe5 27. dxc6 f6 28. Re4 proves good enough, as Black can’t put up a defense despite his nominal material edge. Black’s queen gets in a few spite checks, but his position is hopeless when the White king reaches shelter: 34. Nf3 Qe2+ 35. Kh3 Qf1+ 36. Kh4 Qc1 37. Rxf6, and Black resigns, facing lines such as 37. … Rg8 38. Qe6 Rh7 39. Bxh7 Kxh7 40. Rf7+ Rg7 41. Qf5+ Kh8 42. Rf8+ Rg8 43. Qf6+ Kh7 44. Rf7+ Rg7 45. Qxg7 mate.

Karjakin-Caruana, 5th Masters, Sao Paolo, September 2012

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O b5 6. Bb3 Bc5 7. c3 d6 8. d4 Bb6 9. Be3 O-O 10. Nbd2 Bb7 11. Re1 exd4 12. cxd4 Nb4 13. Qe2 c5 14. a3 Nc6 15. d5 Ne7 16. h3 Re8 17. Bc2 Ng6 18. b3 Ba5 19. Rab1 Bc3 20. Rec1 b4 21. a4 a5 22. Bd3 h6 23. Qd1 Ba6 24. Bc2 Ra7 25. Kh2 Rae7 26. g4 Nxe4 27. Nxe4 Rxe4 28. Bxe4 Rxe4 29. Qc2 Qe7 30. Rg1 Rxe3 31. fxe3 Qxe3 32. Rbf1 Be2 33. Qf5 Bd3 34. Qd7 Be5+ 35. Kh1 Be4 36. Qe8+ Nf8 White resigns.

Zimmer-Colas, U.S. Chess League, September 2012

1. c4 e6 2. g3 d5 3. Bg2 Nf6 4. Nf3 Be7 5. O-O O-O 6. Qc2 Nbd7 7. d3 c6 8. b3 e5 9. Bb2 d4 10. Nbd2 Qc7 11. Rae1 c5 12. e3 Bd6 13. b4 dxe3 14. fxe3 cxb4 15. d4 Rb8 16. c5 exd4 17. exd4 b6 18. c6 Ba6 19. Rf2 Rbc8 20. Ng5 h6 21. Nge4 Bb5 22. Nxf6+ Nxf6 23. Rxf6 gxf6 24. Qf5 Bxc6 25. d5 Be5 26. Bxe5 fxe5 27. dxc6 f6 28. Re4 Kh8 29. Rh4 Qg7 30. Be4 Rc7 31. Rg4 Qe7 32. Rg6 Qc5+ 33. Kg2 Qe3 34. Nf3 Qe2+ 35. Kh3 Qf1+ 36. Kh4 Qc1 37. Rxf6 Black resigns.

• David R. Sands can be reached at 202/636-3178 or by email at dsands@washingtontimes.com.