What is semi-tarrasch?

Semi-Tarrasch is a chess opening that arises after 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c5. It is named after the chess player Siegbert Tarrasch, who advocated the Tarrasch Defense (3...Nf6) against 1.d4. The Semi-Tarrasch typically leads to positions with pawn tension in the center and on the queenside, giving both sides chances for tactical play.

One of the key ideas for Black is to use the move cxd4 to open up the c-file for the queen and rook. White has several options, including the aggressive 5.cxd5 exd5 6.Bg5, or the more solid 5.e3 or 5.c5. Black can also try to gain space with moves like ...b6 and ...Bb7, or aim to break through in the center with ...d4.

The Semi-Tarrasch can lead to a range of different positions depending on the player's style and preferences. It is considered a flexible and dynamic opening that allows for creative play and tactical opportunities for both sides.