H\"older Error Bounds and H\"older Calmness with Applications to Convex Semi-Infinite Optimization

Using techniques of variational analysis, necessary and sufficient subdifferential conditions for H\"older error bounds are investigated and some new estimates for the corresponding modulus are obtained. As an application, we consider the setting of convex semi-infinite optimization and give a characterization of the H\"older calmness of the argmin mapping in terms of the level set mapping (with respect to the objective function) and a special supremum function. We also estimate the H\"older calmness modulus of the argmin mapping in the framework of linear programming.Comment: 25 page

Critical point results and their applications

The purpose of this paper is to study the concept of a critical point in complete cone metric spaces and its application in Ekeland type variational principle. For this, we consider the concept of a λ-space, which is weaker than a cone metric space in general. Actually, we rectify some critical point results in λ-spaces, and complete cone metric spaces. Indeed, we try to correct some gaps in some definitions and main results of the previous works and apply them in the set valued case. Moreover, we give an improved version of Ekeland type variational principle in complete cone metric spaces.Publisher's Versio

Ekeland-type variational principle with applications to nonconvex minimization and equilibrium problems

The aim of the present paper is to establish a variational principle in metric spaces without assumption of completeness when the involved function is not lower semicontinuous. As consequences, we derive many fixed point results, nonconvex minimization theorem, a nonconvex minimax theorem, a nonconvex equilibrium theorem in noncomplete metric spaces. Examples are also given to illustrate and to show that obtained results are proper generalizations

Necessary Conditions for Non-Intersection of Collections of Sets

This paper continues studies of non-intersection properties of finite collections of sets initiated 40 years ago by the extremal principle. We study elementary non-intersection properties of collections of sets, making the core of the conventional definitions of extremality and stationarity. In the setting of general Banach/Asplund spaces, we establish new primal (slope) and dual (generalized separation) necessary conditions for these non-intersection properties. The results are applied to convergence analysis of alternating projections.Comment: 26 page

Characterizations of quasi-metric and G-metric completeness involving w-distances and fixed points

[EN] Involving w-distances we prove a fixed point theorem of Caristi-type in the realm of (non -necessarily T-1) quasi-metric spaces. With the help of this result, a characterization of quasi-metric completeness is obtained. Our approach allows us to retrieve several key examples occurring in various fields of mathematics and computer science and that are modeled as non-T-1 quasi-metric spaces. As an application, we deduce a characterization of complete G-metric spaces in terms of a weak version of Caristi's theorem that involves a G-metric version of w-distances.Karapinar, E.; Romaguera Bonilla, S.; Tirado Peláez, P. (2022). Characterizations of quasi-metric and G-metric completeness involving w-distances and fixed points. Demonstratio Mathematica (Online). 55(1):939-951. https://doi.org/10.1515/dema-2022-017793995155

Relative Pareto Minimizers to Multiobjective Problems: Existence and Optimality Conditions

In this paper we introduce and study enhanced notions of relative Pareto minimizers to constrained multiobjective problems that are defined via several kinds of relative interiors of ordering cones and occupy intermediate positions between the classical notions of Pareto and weak Pareto efficiency/minimality. Using advanced tools of variational analysis and generalized differentiation, we establish the existence of relative Pareto minimizers to general multiobjective problems under a refined version of the subdifferential Palais-Smale condition for set-valued mappings with values in partially ordered spaces and then derive necessary optimality conditions for these minimizers (as well as for conventional efficient and weak efficient counterparts) that are new in both finite-dimensional and infinite-dimensional settings. Our proofs are based on variational and extremal principles of variational analysis; in particular, on new versions of the Ekeland variational principle and the subdifferential variational principle for set-valued and single-valued mappings in infinite-dimensional spaces