“…In [15], a proximal bundle method was presented for an unconstrained non-convex problem, which was subsequently applied to the nonsmooth non-convex constrained optimization problem using the improvement function in [12,13]. In view of the applications in [7,10,9,14,20,26,28], it has been shown that the proximal point method is an efficient tool that can transform certain problems into a sequence of easily solvable sub-problems, and many popular algorithms have been adopted. However, the global optimization issue has seldom been addressed in these studies.…”