1,721,004 research outputs found

    A characterization of absolutely summing operators by means of McShane integrable functions

    Full text link
    In [2] Diestel characterized absolutely summing operators between Banach spaces by means of Pettis integrable strongly measurable functions. As the class of Pettis integrable strongly measurable functions is a proper subset of that of McShane integrable ones, it seems natural to ask if the analogous characterization holds considering McShane integrable functions. In this lecture the results about this characterization are presente

    Riemann type integrals for functions taking values in a locally convex space

    Full text link
    The McShane and Kurzweil-Henstock integrals for functions taking values in a locally convex space are dened and the relations with other integrals are studied. A characterization of locally convex spaces in which Henstock Lemma holds is given

    On weakly measurable stochastic processes and absolutely summing operators

    Full text link
    summary:A characterization of absolutely summing operators by means of McShane integrable stochastic processes is considered

    Strongly measurable Kurzweil-Henstock type integrable functions and series

    No full text
    We give necessary and sufficient conditions for the scalar Kurzweil-Henstock integrability and the Kurzweil-Henstock-Pettis integrability of functions f:[1,infty)ightarrowXf:[1, infty) ightarrow X defined as f=sumn=1inftyxnchi[n,n+1)f=sum_{n=1}^infty x_n chi_{[n,n+1)}. Also the variational Henstock integrability is considere

    The method of lower and upper solutions for second order periodic Stieltjes differential equations

    Full text link
    As an application of the Schauder Fixed Point Theorem, an existence theory is developed for second order nonlinear differential equations with Stieltjes derivative related to a left-continuous, nondecreasing function. By the method of lower and upper solutions, under a Nagumo-type assumption we get a very general result which can be further applied to deduce the existence of solutions for second order nonlinear problems in the settings of impulsive differential equations, time scale analysis or generalized differential equations

    Stieltjes differential problems with general boundary value conditions. Existence and bounds of solutions

    No full text
    We are concerned with first order set-valued problems with very general boundary value conditions {ug(t)F(t,u(t)),μg-a.e.t[0,T],L(u(0),u(T))=0\begin{cases} u'_g(t)\in F(t,u(t)),\quad\mu_g \text{-a.e.} t\in[0,T] , \\ L(u(0), u(T))=0 \end{cases} involving the Stieltjes derivative with respect to a left-continuous nondecreasing function g ⁣:[0,T]Rg\colon[0,T]\to\mathbb{R}, a Carathéodory multifunction F ⁣:[0,T]×RP(R)F\colon[0,T]\times\mathbb{R}\to\mathcal{P}(\mathbb{R}) and a continuous L ⁣:R2RL\colon\mathbb{R}^2\to\mathbb{R}. Using appropriate notions of lower and upper solutions, we prove the existence of solutions via a fixed point result for condensing mappings. In the periodic single-valued case, combining an existence theory for the linear case with a recent result involving lower and upper solutions (which can be seen as a consequence of our existence theorem mentioned before), we get not only the existence of solutions, but also lower and upper bounds, respectively, by imposing an estimation for the right-hand side

    Convergence Theorems for Varying Measures Under Convexity Conditions and Applications

    Full text link
    In this paper, convergence theorems involving convex inequalities of Copson’s type (less restrictive than monotonicity assumptions) are given for varying measures, when imposing convexity conditions on the integrable functions or on the measures. Consequently, a continuous dependence result for a wide class of differential equations with many interesting applications, namely measure differential equations (including Stieltjes differential equations, generalized differential problems, impulsive differential equations with finitely or countably many impulses and also dynamic equations on time scales) is provided

    Relaxation Theorem for Stieltjes Differential Inclusions on Infinite Intervals

    Full text link
    For a very general first-order differential problem on an infinite-time horizon involving the Stieltjes derivative with respect to a left-continuous non-decreasing function g:[0,infinity)-> R\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}g:[0,)Rg:[0,\infty )\rightarrow \mathbb {R}\end{document}xg '(t)is an element of F(t,x(t)),t is an element of[0,infinity)x(0)=x0,\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}{xg(t)F(t,x(t)),  t[0,)x(0)=x0,\begin{aligned} \left\{ \begin{array}{l} x'_g(t) \in F(t,x(t)),\; t\in [0,\infty )\\ x(0)=x_0, \end{array} \right. \end{aligned}\end{document}we study the possibility to approximate the solutions of the convexified inclusion by the solutions of the non-convexified problem. Via a generalization to this framework of a classical result concerning continuous selection of trajectory, we thus present a relaxation theorem which states that, similarly to the setting of usual differential inclusions, the approximation can be achieved once we allow to the initial value to differ (but remaining close to) from the initial value of the considered solution of the relaxed inclusion

    Vitali Theorems for Varying Measures

    Full text link
    The classical Vitali theorem states that, under suitable assumptions, the limit of a sequence of integrals is equal to the integral of the limit functions. Here we consider a Vitali type theorem of the following form fndmnfdm\int f_n\,dm_n \rightarrow \int f \,dm for a sequence of pair (fn,mn)n(f_n, m_n)_n and we study its asymptotic properties. The results} are presented for scalar, vector and multivalued sequences of mnm_n-integrable functions fnf_n. The convergences obtained, in the vector and multivalued settings, are in the weak or in the strong sense for Pettis and McShane integrability. A list of known results on this topic is cited and new results are obtained when the ambient space Ω\Omega is not compact

    An equivalent definition of the vector-valued McShane integral by means of partitions of unity

    Full text link
    An integral for vector-valued functions on a σ-finite outer regular quasi-radon measure space is defined by means of partitions of unity and it is shown that it is equivalent to the McShane integral. The multipliers for both the McShane and Pettis integrals are characterize
    corecore