Equation Icon  f ↦→ f + ℒ (¯g + f) , ¯g ↦→ ¯g , (4.1 ) αβ αβ v αβ αβ αβ fαβ ↦→ fαβ + ℒvfαβ, ¯gαβ ↦→ ¯gαβ + ℒvg¯α β. (4.2 )