theorem escortPartitionZn_hasDerivAt
(x : Fin J → ℝ) (hx : ∀ j, 0 < x j) (ρ : ℝ) (n : ℕ) :
HasDerivAt (fun p => escortPartitionZn x p n)
(escortPartitionZn x ρ (n + 1)) ρ := by
unfold escortPartitionZn
convert HasDerivAt.sum (u := Finset.univ)
(fun j _ => hasDerivAt_rpow_logpow (hx j) ρ n) using 1
ext p; simpThe Cumulant Tower: Higher-Order Bridges Between CES and Escort Statistics