The Semi-Slav, Koomen Variation is a variation of the Queen's Gambit Declined, catalogued as ECO D31. The line runs 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. e3 b5 6. a4 Bb4 7. Bd2 Qe7, reaching the position shown below after 14 half-moves.
White holds the centre with pawns on d4, and one pawn capture is available, so the structure has not settled yet. White is ahead in development, with three minor pieces out to Black's one, and Black is up a pawn of material. It is White to move after seven moves. Black has doubled pawns on the c-file.
On the Queen's Gambit Declined generally: A solid and respected response to the Queen's Gambit. Black maintains a strong central presence.
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The Semi-Slav, Koomen Variation goes 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. e3 b5 6. a4 Bb4 7. Bd2 Qe7. It is a variation of the Queen's Gambit Declined and is catalogued as ECO D31.
The Semi-Slav, Koomen Variation is ECO D31. ECO codes group openings by their move order, so nearby codes cover closely related lines of the Queen's Gambit Declined.
Stockfish evaluates the position after 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. e3 b5 6. a4 Bb4 7. Bd2 Qe7 at +0.43 at depth 18, which is a slight pull for White, within normal opening margins. Engine evaluation is only a starting point — at club level the practical value of a line is mostly about whether you know its plans better than your opponent does.
White holds the centre with pawns on d4, and one pawn capture is available, so the structure has not settled yet. White is ahead in development, with three minor pieces out to Black's one, and Black is up a pawn of material. It is White to move. Black has doubled pawns on the c-file.