Equation Icon  ∫ ⟨f,f ⟩ = dx√ −-gf (x )𝒢αβ,γδ(g)f (x), T αβ γδ 1 (2.40 ) 𝒢 αβ,γδ(g) = --(g αγgβδ + g αδg βγ + Cg αβg γδ), 2