Alapin Variation, Barmen Defense, Central Exchange

The Central Exchange is the branch of the Barmen Defense in which Black releases the central tension immediately with 4...cxd4 5. cxd4, then follows with 5...Nc6 and 6...Bg4. This departs from the usual practice of delaying the exchange. The trade gives the c3-square back to White's knight, but it leaves White with an isolated d-pawn, and the queen on d5, the knight on c6 and the pin on the f3-knight all bear down on d4. White has an open game with good development and space, and Black has a clear target.

The two main replies are almost equally popular. 7. Nc3 develops with gain of tempo on the queen and allows the Endgame Variation, 7...Bxf3 8. gxf3 Qxd4 9. Qxd4 Nxd4. In that line Black wins the d-pawn and forces the queens off, while White gets doubled f-pawns and active pieces in return. 7. Be2 breaks the pin first and prepares to castle. 7. Be3, which defends d4 directly, is much less common. The engine gives White a slight edge, and White scores well in practice.