Nonsmooth KKT-type optimality and duality for multiobjective fractional bilevel optimization via tangential subdifferentials

This paper studies a class of nondifferentiable multiobjective fractional bilevel optimization problems. Under suitable nonsmooth constraint qualifications, necessary optimality conditions of the Karush– Kuhn–Tucker (KKT) type are established using tangential subdifferentials. Sufficient optimality conditions are further derived under Dini generalized convexity assumptions characterized through tangential subdifferential. Moreover, nonsmooth Wolfe-type dual models are formulated for the considered problems, and both weak and strong duality theorems are proved under appropriate convexity hypotheses. Numerical examples are provided to illustrate the applicability of the theoretical results.