theorem curvatureK_sign_classification (hJ : 2 ≤ J) (ρ : ℝ) :
(ρ < 1 → 0 < curvatureK J ρ) ∧
(ρ = 1 → curvatureK J ρ = 0) ∧
(1 < ρ → curvatureK J ρ < 0) := by
refine ⟨curvatureK_pos hJ, fun h => ?_, fun h => ?_⟩
· simp [curvatureK, h]
· unfold curvatureK
apply div_neg_of_neg_of_pos
· have : (1 : ℝ) < ↑J := by exact_mod_cast (by omega : 1 < J)
nlinarith
· exact_mod_cast (by omega : 0 < J)Multi-Agent CES Game Theory (Gap #14)