theorem curvatureK_real_concave_derivative {J ρ : ℝ} (hJ : 0 < J) (hρ : ρ < 1) : -2 * (1 - ρ) / J ^ 3 < 0 := by apply div_neg_of_neg_of_pos · nlinarith · positivity
thesis/CESProofs/EntryExit/CurvatureInJ.lean:40
Paper 1c, Section 2: K(J) as the Network Engine