Maximal Regularity for Non-autonomous Equations with Measurable Dependence on Time

In this paper we study maximal L ^p -regularity for evolution equations with time-dependent operators A. We merely assume a measurable dependence on time. In the first part of the paper we present a new sufficient condition for the L ^p -boundedness of a class of vector-valued singular integrals which does not rely on Hörmander conditions in the time variable. This is then used to develop an abstract operator-theoretic approach to maximal regularity. The results are applied to the case of m-th order elliptic operators A with time and space-dependent coefficients. Here the highest order coefficients are assumed to be measurable in time and continuous in the space variables. This results in an L ^p (L ^q )-theory for such equations for \(p,q\in (1, \infty )\). In the final section we extend a well-posedness result for quasilinear equations to the time-dependent setting. Here we give an example of a nonlinear parabolic PDE to which the result can be applied.     

On a Perturbed System of Volterra Integral Equations

In this paper, we study the existence, uniqueness, and other properties of solutions of a system of Volterra integral equations under a general class of perturbations. The representation formula, a simple and classic application of the Leray–Schauder alternative, and a certain integral inequality with explicit estimate are used to establish the results.     

广义Volterra积分方程一类最大最小解的存在性

本文考虑Banach 空间中形如x(t)= u(t)+ ∫Gtf(t,s,x(s))ds的广义Volterra 积分方程,通过引入一类偏序证明了所述方程相应的最大最小解的存在性.     

Asymptotics of the Solutions to Singularly Perturbed Multidimensional Integral Equations

Asymptotics of solutions to the equations εh_ε + Rh_ε = f as ε → + 0 is studied for a class of multidimensional integral equations that are basic in estimation theory.     

奇摄动Volterra型积分微分方程Robin问题

本文利用上、下解证明了Volterra型积分微分方程解的存在性。然后，应用所获得的微分不等式理论，在适当的假设下，通过构造特殊的上、下解函数，证明Volterra型 奇摄动积分微分方程解的存在性，并给出一致有效的解的渐近估计。     

On a Series Representation for Integral Kernels of Transmutation Operators for Perturbed Bessel Equations

A representation for the kernel of the transmutation operator relating a perturbed Bessel equation to the unperturbed one is obtained in the form of a functional series with coefficients calculated by a recurrent integration procedure. New properties of the transmutation kernel are established. A new representation of a regular solution of a perturbed Bessel equation is given, which admits a uniform error bound with respect to the spectral parameter for partial sums of the series. A numerical illustration of the application of the obtained result to solve Dirichlet spectral problems is presented.     

Integral Equations on Function Spaces and Dichotomy on the Real Line

The purpose of this paper is to give new and general characterizations for uniform dichotomy and uniform exponential dichotomy of evolution families on the real line. We consider two general classes denoted and and we prove that if V,W are Banach function spaces with and , then the admissibility of the pair for an evolution family implies the uniform dichotomy of . In addition, we consider a subclass and we prove that if , then the admissibility of the pair implies the uniform exponential dichotomy of the family . This condition becomes necessary if . Finally, we present some applications of the main results.     

Regularity Properties of Perturbed Hille—Yosida Operators and Retarded Differential Equations

In this work we give sufficient conditions on the semigroup (T ₀ (t)) _t\geq0 , generated by the part of a Hille—Yosida operator in the closure of its domain, in order that certain perturbations preserve some regularity properties of (T ₀ (t)) _t\geq0 , like the norm continuity, compactness and differentiability. An application of our abstract results to retarded differential equations is given. May 22, 2000     

Regularity of Backward Stochastic Volterra Integral Equations in Hilbert Spaces

This article investigates backward stochastic Volterra integral equations in Hilbert spaces. The existence and uniqueness of their adapted solutions is reviewed. We establish the regularity of the adapted solutions to such equations by means of Malliavin calculus. For an application, we study an optimal control problem for a stochastic Volterra integral equation driven by a Hilbert space-valued fractional Brownian motion. A Pontryagin-type maximum principle is formulated for the problem and an example is presented.     

Baillon's Theorem on Maximal Regularity

The aim of this note is to give a proof of Baillon's Theorem on Maximal Regularity. Though it is in some sense a negative result (it states that for abstract Cauchy problems maximal regularity can occur only in very special cases), it is commonly accepted that it is important. Many people believe that its proof is very complicated. This might be due to the fact that Baillon's note in the Comptes Rendus is rather short and sometimes difficult to understand. The proof outlined here follows basically Baillon's lines. However it is simplified and (hopefully) easier to understand.     

Fractional Multistep Methods for Weakly Singular Volterra Integral Equations of the First Kind with Perturbed Data

ABSTRACT

Fractional multistep methods were introduced by C. Lubich for the quadrature of Abel integral operators and the solution of weakly singular Volterra integral equations of the first kind with exactly given right-hand sides. In the current paper, we consider the regularizing properties of these methods to solve the mentioned integral equations of the first kind for perturbed right-hand sides. Finally, numerical results are presented.     

向量值柯西问题的适定性

设A为复Banach空间X上的稠定闭算子.我们证明了若抽象柯西问题具有C-适定性,则{λ∈C:Reλ≥0）　ρ（A）且存在C>0,使得任给λ∈C,Reλ≥0,都有（λ-A）-1≤C/1+　λ.因而A必为X上某一有界解析半群的无穷小生成元.对于定义在有限区间[0,T]上的抽象柯西问题,我们亦得到了类似的结果.     

Singul arl y Perturbed Dirichl et Problem for A Class of Integral Differential Elliptic Equations

<正> Consider the singularly perturbed Dirichlet problem of similinear integral differential elliptic equations L_ε[u]=εL_1[u]+L_2[u]=f(x, u, Tu, ε), x=(x_1, x_2,..., x_n)∈R~n, (1) u|(?)=g(x, ε) (2)where     

直线上带平移的奇异积分方程的解

该文讨论了直线上带实平移或复平移的奇异积分方程的解，获得了方程的可解条件，证明了方程解的唯一性，给出了方程有解的情况下解的积分或级数表达式。     

Regularity of the Fractional Maximal Function

The purpose of this work is to show that the fractional maximaloperator has somewhat unexpected regularity properties. Themain result shows that the fractional maximal operator mapsL^p-spaces boundedly into certain first-order Sobolev spaces.It is also proved that the fractional maximal operator preservesfirst-order Sobolev spaces. This extends known results for theHardy-Littlewood maximal operator. 2000 Mathematics SubjectClassification 42B25, 46E35.