Equation Icon  ∮ ∮ ⟨ ¯ ⟩ 1- ¯ A ⟨ ¯ ⟩ 1- ¯ A Φ0 (t,s) = 𝒜 S(t,s)Φ0 (t,s,𝜃 )d𝒜, Φa (t,s) = 𝒜 S (t,s)Φa (t,s,𝜃 )d𝒜, (17.25 )