arXiv subjects

M. Ruiz Galan

Publications and source records attributed to M. Ruiz Galan.

4 recordsLinked to original sources

arXiv2020

A perturbed collage theorem and its application to inverse interval integral problems

This paper deals with inverse problems subject to imprecise or vague information of some involved data by means of interval-valued functions. To provide interval solutions to the inverse problems we have adopted a perturbed collage-based approach and we have also introduced a numerical procedure by means of the use of interval bases in a sense. To illustrate the results, and as an application, we have studied the Volterra interval-valued integral equation, and provide some computational examples.

math.NA↗

arXiv2019

Using the Generalized Collage Theorem for Estimating Unknown Parameters in Perturbed Mixed Variational Equations

In this paper, we study a mixed variational problem subject to perturbations, where the noise term is modelled by means of a bilinear form that has to be understood to be "small" in some sense. Indeed, we consider a family of such problems and provide a result that guarantees existence and uniqueness of the solution. Moreover, a stability condition for the solutions yields a Generalized Collage Theorem, which extends previous results by the same authors. We introduce the corresponding Galerkin method and study its convergence. We also analyze the associated inverse problem and we show how to solve it by means of the mentioned Generalized Collage Theorem and the use of adequate Schauder bases. Numerical examples show how the method works in a practical context.

math.NA↗

arXiv2017

Revisiting the Hahn-Banach Theorem and Nonlinear Infinite Programming

[REVISED VERSION] The aim of this paper is to state a sharp version of the König supremum theorem, an equivalent reformulation of the Hahn--Banach theorem. We apply it to derive statements of the Lagrange multipliers, Karush-Kuhn-Tucker and Fritz John type, for nonlinear infinite programs. We also show that a weak concept of convexity coming from minimax theory, infsup-convexity, is the adequate one for this kind of results.

math.FA↗

arXiv2017

A theorem of the alternative with an arbitrary number of inequalities and quadratic programming

In this paper we are concerned with a Gordan-type theorem involving an arbitrary number of inequality functions. We not only state its validity under a weak convexity assumption on the functions, but also show it is an optimal result. We discuss generalizations of several recent results on nonlinear quadratic optimization, as well as a formula for the Fenchel conjugate of the supremum of a family of functions, in order to illustrate the applicability of that theorem of the alternative.

math.OC↗