Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation

The Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation is a chess opening that involves a strategic pawn structure and active piece development.

The Semi-Tarrasch Defense is a variation of the Queen's Gambit Declined where Black aims to establish a solid pawn structure while maintaining flexibility in piece development. The San Sebastian Variation specifically focuses on a move order that involves exchanging pawns on d4 and c5.

The opening begins with White playing 1. d4, to which Black responds with 1... Nf6. White then continues with 2. c4, and Black plays 2... e6, preparing to establish a solid pawn structure. White follows up with 3. Nf3, developing the knight and preparing to control the center.

Black continues with 3... d5, challenging White's central pawn on d4. White responds with 4. Nc3, reinforcing the central pawn and preparing for further development. Now, Black plays 4... c5, aiming to exchange pawns and open up the position.

White captures on d5 with 5. cxd5, and Black recaptures with 5... Nxd5, maintaining a balanced pawn structure. White then plays 6. e4, aggressively attacking the knight on d5. Black responds with 6... Nxc3, exchanging knights and opening up the position further.

White captures on c3 with 7. bxc3, and Black plays 7... cxd4, opening up the center and creating potential for piece activity. White continues with 8. cxd4, and Black plays 8... Bb4+, pinning the white king's knight to the queen.

White responds with 9. Bd2, breaking the pin and developing the bishop. Finally, Black plays 9... Qa5, attacking the white bishop and preparing to complete piece development.

In summary, the Queen's Gambit Declined: Semi-Tarrasch Defense, San Sebastian Variation involves a strategic pawn structure and active piece development, with Black aiming to establish a solid position while maintaining flexibility.