The Semi-Tarrasch Defense, Main Line is a variation of the Queen's Gambit Declined, catalogued as ECO D42. The line runs 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 c5 5. cxd5 Nxd5 6. e3 Nc6 7. Bd3, reaching the position shown below after 13 half-moves.
White holds the centre with pawns on d4, and one pawn capture is available, so the structure has not settled yet. Development is level at three minor pieces each. It is Black to move after seven moves.
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-Tarrasch Defense, Main Line goes 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 c5 5. cxd5 Nxd5 6. e3 Nc6 7. Bd3. It is a variation of the Queen's Gambit Declined and is catalogued as ECO D42.
The Semi-Tarrasch Defense, Main Line is ECO D42. 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 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 c5 5. cxd5 Nxd5 6. e3 Nc6 7. Bd3 at +0.12 at depth 18, which is balanced. 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. Development is level at three minor pieces each. It is Black to move.