Sicilian Defense, Richter-Rauzer Variation

The Richter-Rauzer Variation arises after Black develops the knights to f6 and c6 and White plays 6.Bg5. The bishop attacks the f6-knight, an important defender of the central squares, and creates a relative pin: if the knight moves, Black's queen on d8 may be exposed. The pinned piece can legally move, but the cost must be calculated.

White commonly follows with Qd2, queenside castling, which places the king on c1 and the a1-rook on d1, and f4. The aim is not only a king attack. White also increases pressure on d5 and e6, tries to prevent a central break, meaning a pawn advance that opens or transforms the center, and may use the d-file, the vertical line from d1 to d8, if no pawns block it. Black commonly answers with ...e6, ...Be7, and kingside castling, although more dynamic plans exist.

Why Bg5 changes the position

• It limits the freedom of the f6-knight and may force Black to decide whether to chase, exchange, or tolerate the bishop.
• It makes Qd2 and queenside castling easier because the c1-bishop has already developed.
• It means pawn advances such as ...d5 or ...e5 must be checked for concrete captures and threats rather than played by habit.

The Richter-Rauzer differs from the Sozin Attack, where White's bishop goes to c4 and points directly at f7. Both can be aggressive, but the bishop uses a different diagonal and creates different priorities.