theorem fifth_role_of_K (hJ : 2 ≤ J) {ρ : ℝ} (hρ : ρ < 1) (hρ0 : ρ ≠ 0)
{c : ℝ} (hc : 0 < c) :
-- K is positive (economic curvature exists)
0 < curvatureK J ρ ∧
-- K decomposes as bridge × geometry × Fisher
curvatureK J ρ =
bridgeRatio ρ * (↑J - 1) * c ^ 2 * escortFisherEigenvalue J ρ c ∧
-- The bridge theorem holds
-hessLogFEigenvalue J ρ c =
bridgeRatio ρ * escortFisherEigenvalue J ρ c :=
⟨curvatureK_pos hJ hρ,
curvatureK_eq_bridge_times_fisher hρ0 hc.ne' (Nat.cast_ne_zero.mpr (by omega)),
bridge_theorem hρ0 hc.ne' (Nat.cast_ne_zero.mpr (by omega))⟩Information Geometry of CES: