Equation Icon  1( ′ ′ ) (φ;a) (φ;b) → -- gap∇p ′∇b + gbp∇a ∇p ′ φ (x )φ(x′), 2( ) φ (φ ) → 1- ∇ ∇ + g p′gq′∇ ′∇ ′ φ (x )φ(x′). ;ab 2 a b a b p q