theorem antisym_total_sum_zero {A : Fin N → Fin N → ℝ}
(hA : IsAntisymmetric A) :
∑ i, ∑ j, A i j = 0 := by
have key : ∀ i j : Fin N, A i j = -A j i := hA
have h : ∑ i, ∑ j, A i j = -(∑ i, ∑ j, A i j) := by
conv_lhs =>
rw [Finset.sum_comm]
arg 2; ext y; arg 2; ext x
rw [key x y]
simp only [Finset.sum_neg_distrib]
linarithResults 36-46: Conservation Laws and Symmetry Identities