ECO E12 · Queen's Indian Defense
Queen's Indian Defense: Petrosian Variation
The position after 1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.a3.
1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. a3
Queen's Indian Defense: Petrosian Variation is filed under ECO E12, a variation of Queen's Indian Defense. It is the position after 1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.a3 — 7 half-moves in, with Black to move. Named theory ends here; beyond this the position is yours to work out.