The Semi-Tarrasch Defense, Symmetrical Variation is a variation of the Queen's Gambit Declined, catalogued as ECO D40. The line runs 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Nf3 c5 5. e3 Nc6 6. Bd3 Bd6 7. O-O O-O, reaching the position shown below after 14 half-moves.
Both sides have pawns in the centre (White on d4, Black on d5), and two pawn captures are available, so the structure is still fluid. Development is level at three minor pieces each. It is White to move after seven moves. Both kings have castled kingside, so play tends to shift to the centre and the opposite flank.
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, Symmetrical Variation goes 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Nf3 c5 5. e3 Nc6 6. Bd3 Bd6 7. O-O O-O. It is a variation of the Queen's Gambit Declined and is catalogued as ECO D40.
The Semi-Tarrasch Defense, Symmetrical Variation is ECO D40. 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 Nf6 4. Nf3 c5 5. e3 Nc6 6. Bd3 Bd6 7. O-O O-O at +0.37 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.
Both sides have pawns in the centre (White on d4, Black on d5), and two pawn captures are available, so the structure is still fluid. Development is level at three minor pieces each. It is White to move. Both kings have castled kingside, so play tends to shift to the centre and the opposite flank.