Optimality and duality in nonsmooth multiobjective optimization involving generalized type I functions

A nonsmooth multiobjective optimization problem involving generalized Type I vectorvalued functions is considered. Karush-Kuhn-Tucker type necessary and sufficient optimality conditions are obtained for a feasible point to be an efficient or properly efficient solution. Duality theorems are proved for Wolfe type and Mond-Weir type duals under the generalized Type I assumptions.