theorem cesHessianQF_neg_semidef (hJ : 0 < J) {ρ : ℝ} (hρ : ρ < 1)
{c : ℝ} (hc : 0 < c)
(v : Fin J → ℝ) (hv : orthToOne J v) :
cesHessianQF J ρ c v ≤ 0 := by
rw [cesHessianQF_on_perp hJ ρ c hc v hv]
apply mul_nonpos_of_nonpos_of_nonneg
· simp only [cesEigenvaluePerp]
apply div_nonpos_of_nonpos_of_nonneg
· linarith
· apply mul_nonneg
· exact Nat.cast_nonneg J
· linarith
· simp only [vecNormSq]
apply Finset.sum_nonneg
intro j _
exact sq_nonneg (v j)Gradient and Hessian of CES at the symmetric point.