theorem sectorEffectiveCurvature_nonneg (e : NSectorEconomy N) (n : Fin N) :
0 ≤ sectorEffectiveCurvature e n := by
unfold sectorEffectiveCurvature
exact effectiveCurvatureKeff_nonneg (e.hJ n) (e.hρ n) (e.T n)
(sectorCriticalFriction e n)Multiplier-Cycle Duality in a Multi-Sector Economy