theorem knockout_no_failure (ρ : ℝ) (hJ : 0 < J) :
knockoutRetained J ρ 0 = 1 := by
simp only [knockoutRetained, Nat.cast_zero, sub_zero]
split_ifs with h
· rw [div_self (Nat.cast_ne_zero.mpr (by omega))]
simp
· rflFurther properties of CES curvature (Paper 1, Section 9):