Equation Icon  guu = 0, (10.39 ) ua a g = − Ω , (10.40 ) ab ab ( a b a b) 1-2 ab 1- 2( a b a b) 3 g = δ + r a Ω + Ω a + 3r S + 3 r S Ω + Ω S + O (r ). (10.41 )