E57 Nimzo-Indian, 4.e3, Main line with 8...dc and 9...cd (1 d4 Sf6 2 c4 e6 3 Sc3 Lb4 4 e3 O-O 5 Sf3 d5 6 Ld3 c5 7 O-O Sc6 8 a3 dxc4 9)