Ruy Lopez, Exchange Variation Qf6 7.Qd3. There are two "ECO" classifications for the Exchange Variation. Bibliography Ruy Lopez, Exchange Variation The Exchange Variation of the Ruy Lopez is a chess opening that begins with the moves: Black may recapture on c6 with either pawn; although 4...bxc6 is playable, 4...dxc6 is almost always chosen at master level. Black has gained the at the cost of a weakened pawn structure, due to his doubled pawns on c6 and c7. 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
Tactical decision game Lieutenant?", the games in the "Tactical Problems ..." series were based them on descriptions of actual engagements that took place between 1914 and 1953. Some of these were first-hand accounts written by S.L.A. Marshall, Erwin Rommel,and Friedrich von Mellenthin. Others were secondary works composed by military historians.) Regardless of the actual events that inspired them, all of the problems were modified to reflect the organization and equipment of the 1980s. Thus, none of these historically-inspired games can be classified as decision-forcing cases.) Tactical decision game A tactical decision game is a decision game that puts students in the role of