∀ {α : Type u} [inst : DecidableEq α] {M : Type u_1} [inst_1 : CommMonoid M] (n : α →₀ ℕ) (f : (α →₀ ℕ) → (α →₀ ℕ) → M),
  ∏ p ∈ Finset.antidiagonal n, f p.1 p.2 = ∏ p ∈ Finset.antidiagonal n, f p.2 p.1