theorem
ProbabilityTheory.Copula.RankRegion.RhoTau.weighted_cycle_product
{ι : Type u_1}
[Fintype ι]
(u : ι → ℝ)
(hs : ∑ i : ι, u i = 1)
(a b : ι → ι → ℝ)
(ha : ∀ (i j : ι), a j i = -a i j)
(hb : ∀ (i j : ι), b j i = -b i j)
:
The six mixed terms in the cycle product all reduce to the same rank moment.