Mainline Orthodox Defense

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In chess, the Queen's Gambit Declined, Mainline Orthodox Defense is a response to Queen's Gambit Declined distinguished by the moves 1.d4 d5 2.c4 e6 3. Nc3 or 3.Nf3 followed by 4. Bg5 (the moves are given in algebraic notation). A weakness is black's ability to respond with h6. It is then better (as calculated by Crafty and by the play statistics) to capture the knight at f6 than retreat the bishop. After h6, Bxf6 and Qxf6 the win statistics narrow to just an 8% advantage for white and computer evaluation indicates equality of +0.01. An alternative is the Exchange Variation of 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.cxd5 exd5.

How to play it

• 1.d4 d5 2.c4 e6 3. Nc3 (good for white)

Play statistics are: White won 40% Black won 24% Draw 36% with > 100 games

Crafty 20.14 evaluates this position at a depth = 15 1/34 as -0.05 (+ = advantage for white)

OR

• 1.d4 d5 2.c4 e6 3. Nf3 (recommended for white)

Play statistics are: White won 41% Black won 20% Draw 39% with > 100 games

Crafty 20.14 evaluates this position at a depth 16 1/34 as = +0.02 (+ = advantage for white)

[edit] Queen's Gambit Declined, Mainline Orthodox Defense 1.d4 d5 2.c4 e6 3. Nf3 Nf6 4. Bg5

• 1.d4 d5 2.c4 e6 3. Nf3 Nf6 4. Bg5

Play statistics are: White won 39% Black won 27% Draw 34%

Crafty 20.14 evaluates this position at a depth = 15 4/31 as ++0.00 (+ = advantage for white)

[edit] Queen's Gambit Declined, Mainline Orthodox Defense 1.d4 d5 2.c4 e6 3. Nc3 Nf6 4. Bg5

• 1.d4 d5 2.c4 e6 3. Nc3 Nf6 4. Bg5

Play statistics are: White won 43% Black won 23% Draw 34%

Crafty 20.14 evaluates this position at a depth = 16 10/31 as +0.04 (+ = advantage for white)

1.d4 d5 2.c4 e6 3.Nc3 Nf6 play continues 4.Bg5 Be7 5.Nf3 c6 6.e3 0-0 7.Rc1 Nbd7 8.Bd3 dxc4 9.Bxc4, though the moves are not always played in that order. Black has surrendered the center and stands somewhat cramped, though Black has succeeded in extracting a free move from White. White will try to use his advantage in space to attack; whereas Black will try to keep White at bay while striking back at the center

Other variations include

The Tartakower Defense 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Be7 5.e3 0-0 6.Nf3 h6 7.Bh4 b6, is a solid continuation.