Queen's Gambit Declined: Semi-Slav, Koomen Variation is a chess opening with the ECO code D31, part of the Queen's Gambit Declined family. It goes 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. e3 b5 6. a4 Bb4 7. Bd2 Qe7. White opens with 1. d4 (the queen's pawn) and Black answers 1... d5. After 14 moves it is White to move. After the last move Black is a pawn ahead in material. The lesson on the board explains every move of the line and lets you play it yourself; it is free.
The moves
1. d4 – White plays the pawn to d4
1... d5 – Black plays the pawn to d5
2. c4 – White plays the pawn to c4
2... e6 – Black plays the pawn to e6
3. Nc3 – White plays the knight to c3
3... c6 – Black plays the pawn to c6
4. Nf3 – White plays the knight to f3
4... dxc4 – Black captures on c4 with the d-pawn
5. e3 – White plays the pawn to e3
5... b5 – Black plays the pawn to b5
6. a4 – White plays the pawn to a4
6... Bb4 – Black plays the bishop to b4
The line goes on for 2 more moves; the lesson shows them all.
About the Queen's Gambit Declined
After 1.d4 d5 2.c4, Black keeps the d5 pawn with ...e6 instead of taking on c4. It is solid, classical and very reliable.
Black develops calmly: ...Nf6, ...Be7, ...O-O, and keeps a strong pawn on d5.
The light-squared bishop on c8 is often stuck behind e6; freeing it is a main task.
Black frees the position with the breaks ...c5 or ...e5; White often plays for a minority attack with b4-b5.
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