Ruy Lopez, Exchange Variation
|Moves||1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6|
|Named after||Ruy López de Segura, Libro del Ajedrez, 1561|
|Synonym(s)||Spanish Game, Exchange Variation|
Black may recapture on c6 with either pawn; though 4...bxc6 is playable, 4...dxc6 is almost always chosen at master level. Black has gained the bishop pair at the cost of a weakened pawn structure, due to his doubled pawns on c6 and c7. In the Exchange Variation, by exchanging the "Spanish bishop", the White aims to reach an endgame in which he has the superior pawn structure, which may become an important factor, thus Black is compelled to strive for an active position, generally avoiding piece exchanges.
|This article uses algebraic notation to describe chess moves.|
There are two ECO classifications for the Exchange Variation.
- ECO code C68 covers 4...bxc6 and 4...dxc6, with White's response of 5.d4 or 5.Nc3 to either capture. After 4...dxc6 White should not capture with 5.Nxe5 as 5...Qd4 forks the knight and pawn, thus regaining the material, leading to positions where White has forfeited his structural advantage—the compensation for ceding the two bishops. Black has a variety of playable responses to the popular 4...dxc6 5.0-0 (the Barendregt Variation, which Bobby Fischer played with success). White now threatens 6.Nxe5 because the sequence 6...Qd4 7.Nf3 Qxe4 to regain the pawn, now fails to 8.Re1 pinning and winning the queen. ECO code C68 examines these responses to 5.0-0: 5...Qf6, 5...Qe7, 5...Bd6, 5...Qd6, or 5...Bg4 (all directly defending the e5-pawn, except 5...Bg4 which indirectly defends by pinning the knight). The moves 5...Be6, 5...Be7, and 5...Ne7 are less common moves which have never achieved popularity. The idea behind these moves is that if White plays to win a pawn with 6.Nxe5, 6...Qd4 7.Nf3 Qxe4 is again playable, as the Black minor piece on e6 or e7 blocks the e-file.
- ECO code C69 treats the variations arising from the continuation 4...dxc6 5.0-0 f6.
Barendregt Variation: 5.0-0 
|This section does not cite any references or sources. (July 2012)|
There are several main replies to the Barendregt Variation, 5.0-0.
The most aggressive move against the Barendregt Variation is 5...Bg4. After 6.h3, Black has possibilities such as 6...Bh5 or 6...Bxf3, but the most modern and active variation is 6...h5. White cannot take the bishop with 7.hxg4 because Black plays 7...hxg4, attacking the knight. If the knight moves, 8...Qh4 threatens checkmate with 9...Qh2# or 9...Qh1#. After 8...Qh4, if White tries 9.f3, trying to escape via f2 after a queen check, Black replies 9...g3 with inevitable mate.
After 6...h5, the most common continuation is 7.d3 Qf6 8.Nbd2 Ne7 9.Re1 Ng6 and now an interesting line is: 10.hxg4!?. After 10...hxg4, 11.g3! offering back the piece (White should not try to hold onto the knight, as it would be similar to the position after 7.hxg4?? hxg4). After 11.g3 gxf3 12.Qxf3, White is safe and has the superior pawn structure, which is considered to offer a small advantage in the ensuing queenless middlegame.
A move that was popular amongst masters during Fischer's reign and is still popular today is 5...f6. White's most active and modern approach to this defense is 6.d4, after which Black has two options: 6...Bg4 and 6...exd4. The move 6...Bg4 can be met also by two options: 7.dxe5 and 7.c3. On 7.dxe5 Qxd1 8.Rxd1 fxe5, White cannot take the e5-pawn with the knight because the knight is pinned by the bishop. Multiple trades have occurred, however, bringing the position closer to an endgame, which is beneficial for White since he has the better pawn structure.
The second move against 5...f6 6.d4 is 6...exd4. White should play 7.Qxd4 (Fischer chose the more obscure 7.Nxd4 in two Exchange Variation games in his 1992 match with Boris Spassky), offering a trade of queens which Black should take or else he is clearly worse. After 7...Qxd4 8.Nxd4 c5 9.Nb3 (9.Ne2 is another line; however Fischer often preferred 9.Nb3) and White will develop freely by developing their bishop to e3, their b1 knight to c3 or d2 depending on the position and bringing one of their rooks to d1, usually the rook on f1.
This is often called the Bronstein Variation. White's popular choices are 6.Na3 and 6.d3. After 6.d4 exd4 7.Nxd4, this move permits 7...Bd7 followed by ...0-0-0. Other ways for White to proceed include 6.a4 or 6.c3.
The other main move in the Barendregt Variation is 5...Bd6. White again goes 6.d4, where Black can play either 6...exd4 or 6...Bg4.
The move 6...exd4 is not the best move. White captures the pawn back with 7.Qxd4 and stands clearly better. An example of a massacre where Black is on the losing side is as follows: 7...f6 8.Nc3[note 1] Bg4? 9.e5! attacking the g4-bishop with the queen and the d6-bishop with the pawn. After 9...Bxf3 10. exd6, Black cannot capture the pawn because the f3-bishop is hanging, and after 10...Bh5 11.Re1+ Kf8 12.Qc5, attacking the bishop on h5 while threatening dxc7 discovered check, winning the queen, White has a winning advantage.
The move 6...Bg4 is the better move in this line. White has a couple of possible moves, but the best line is 7.dxe5 Bxf3 8.Qxf3 Bxe5. Numerous trades have occurred, so White is satisfied. After 9.Nd2 Ne7 10.Nc4 Ng6 11.Nxe5 Nxe5 12.Qg3 (Salazar–Smith, Groningen 1976/77), White had the upper hand (Gipslis).
If White can exchange all pieces, he has a big advantage in the endgame, due to the pawn structure. Max Euwe gave the pure pawn ending (without pieces—see diagram) resulting after the exchange of White's d-pawn for Black's e-pawn as a win for White, and the winning procedure is detailed in (Müller & Lamprecht 2007:147–49).
- ECO 2nd edition considers 8.b3, 8.c4, 8.Be3, 8.Nbd2, 8.Rd1, 8.Re1, and 8.e5, with all lines leading to balanced positions.
- de Firmian, Nick (1999), Modern Chess Openings: MCO-14, Random House Puzzles & Games, ISBN 0-8129-3084-3
- Müller, Karsten; Lamprecht, Frank (2007), Secrets of Pawn Endings, Gambit Publications, ISBN 978-1-904600-88-6
- Shaw, John (2003), Starting Out: The Ruy Lopez, Everyman Chess, ISBN 1-85744-321-7
- Taulbut, Shaun (1996), Understanding the Spanish, Batsford, ISBN 978-0-7134-7633-0
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