D31: Queen's Gambit Declined, semi-Slav, Koomen variation

D31 Sub-variants:

• Queen's Gambit Declined, 3.Nc3
  1. d4 d5 2. c4 e6 3. Nc3
• Queen's Gambit Declined, Janowski variation
  1. d4 d5 2. c4 e6 3. Nc3 a6
• Queen's Gambit Declined, Alapin variation
  1. d4 d5 2. c4 e6 3. Nc3 b6
• Queen's Gambit Declined, Charousek (Petrosian) variation
  1. d4 d5 2. c4 e6 3. Nc3 Be7
• Queen's Gambit Declined, semi-Slav
  1. d4 d5 2. c4 e6 3. Nc3 c6
• Queen's Gambit Declined, semi-Slav, Noteboom variation
  1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4
• Queen's Gambit Declined, semi-Slav, Koomen variation
  1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. a4 Bb4 6. e3 b5 7. Bd2 Qe7
• Queen's Gambit Declined, semi-Slav, Junge variation
  1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. a4 Bb4 6. e3 b5 7. Bd2 Qb6
• Queen's Gambit Declined, semi-Slav, Abrahams variation
  1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. a4 Bb4 6. e3 b5 7. Bd2 a5
• Queen's Gambit Declined, semi-Slav, Marshall gambit
  1. d4 d5 2. c4 e6 3. Nc3 c6 4. e4