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The Ruy Lopez, Exchange Variation is a variation of the Ruy Lopez chess opening that begins with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Bb5 a6 :4. Bxc6 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. ==ECO codes== 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ruy Lopez, Exchange Variation」の詳細全文を読む スポンサード リンク
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