Equation Icon  ℒ1 = --1--ga1c1ga2c2ga3c3𝒟 𝒜a aa (t)𝒟 𝒜c c c(t) 2 ⋅ 3! 12 3 1 23 --1-- a1a2a3 = 2 ⋅ 3!𝒟 𝒜a1a2a3(t) 𝒟 𝒜 (t). (9.131 )