Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. Nc3/3...Nf6/4. Nf3/4...e6

A highly theoretical opening. Black willingly keeps the light-squared bishop behind the pawn-chain, intending to free it later with either the e5 or c5 pawn breaks. In response, White has two main options with very different playstyles.

5. Bg5 leads to sharp, tactical positions, where Black can choose to play the Botvinnik variation 5...dxc4 or the Moscow or Anti-Moscow.

5. e3 leads to calmer, more positional variations. White will generally decide whether to go into the mainline Meran with 6. Bd3 or avoid it with one of the many Anti-Meran variations.

Some less popular options include 5. cxd5, leading to either an exchange Slav or exchange Queens gambit declined. 5. g3 is also a viable alternative, dodging theoretical lines of the Semi-Slav and potentially resulting in Catalan-esque positions.

This opening can also be reached through the queen's gambit declined by the move order 2...e6 3. Nc3 Nf6 4. Nf3 c6.

1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. Nf3 e6

Wikipedia has related information at Semi-Slav Defence.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.