equation icon  2 [ (1---2-q)-× g'p'''gq'' (G ' '''G ' '''+ G 'G '' '' ''' 4 c a xy ;bp x y;q d xy;bd xy ;q p + Gyx';q''d'Gy'x;bp'''+ Gyx;bd'Gy'x';q''p''') ''' '' +gd'p gq a(Gxy';bp'''Gx'y;q''c'+ Gxy;bc'Gx'y';q''p''' + Gyx';q''c'Gy'x;bp'''+ Gyx;bc'Gy'x';q''p''') +g 'p'''gq'' (G ' '''G ' '' '+ G 'G '' ''''' c b xy ;ap xy;q d xy;ad xy;q p + Gyx';q''d'Gy'x;ap'''+ Gyx;ad'Gy'x';q''p''') p''' q'' +gd' g b(Gxy';ap'''Gx'y;q''c'+ Gxy;ac'Gx'y';q''p''' ] + Gyx';q''c'Gy'x;ap'''+ Gyx;ac'Gy'x';q''p''') . (64)