Global invexity and duality in mathematical programming

Global invexity is characterized by a condition which is independent of the scale function describing the invexity. Consequently, weak duality holds for the Wolfe, or Mond–Weir, dual problem when a sufficient invexity hypothesis is replaced by a suitable inequality condition. This holds exactly when the Wolfe dual is equivalent to the Lagrangian dual. Result are given for differentiable, and for locally Lipschitz, functions.