theorem chordalDistSq_nonneg (x y : Fin J → ℝ) (c : ℝ) : 0 ≤ chordalDistSq J x y c := by simp only [chordalDistSq, isoquantDistSq] exact Finset.sum_nonneg fun j _ => sq_nonneg _
thesis/CESProofs/Foundations/IsoquantGeometry.lean:238
Differential Geometry of CES Isoquants (Gap #6)