Equation Icon  ∑ P ˙𝒩 + ∑ πm1 ⋅⋅⋅mpA˙(p) = ∑ P′ ˙𝒩 + ∑ ℰi1⋅⋅⋅ip𝒜˙(p) . (2.18 ) ij ij (p) m1⋅⋅⋅mp ij ij (p) m1 ⋅⋅⋅mp i<j p i<j p