The theory of abstract differential equations is a new branch of operator theory and of ordinary differential equations. It is a rapidly developing area of mathematics, and this book presents new results at the forefront of research in this field. Based on the author's own work, this volume covers differential equations in abstract spaces, presenting new and some of the lesser known facts and propositions of the theory. It will be invaluable reading for postgraduate students and research workers in ordinary and partial differential equations, almost-periodic solutions, theory of semigroups of operators and evolution equations.

This looks at a new branch of operator theory and partial differential equations, which in recent years, has become a rapidly growing field of mathematics. Well-posed problems are studied in the context of the theory of operator groups and semigroups as well as the framework of time dependent evolution equations. Non well-posed problems are also considered.

This book presents recent methods of study on the asymptotic behavior of solutions of abstract differential equations such as stability, exponential dichotomy, periodicity, almost periodicity, and almost automorphy of solutions. The chosen methods are described in a way that is suitable to those who have some experience with ordinary differential equations. The book is intended for graduate students and researchers in the related areas.

This collection of counter-examples highlights the theory of differential equations and related topics which is now playing an enormously important role in the area of science, engineering and mathematics.

This reference - based on the Conference on Differential Equations, held in Bologna - provides information on current research in parabolic and hyperbolic differential equations. Presenting methods and results in semigroup theory and their applications to evolution equations, this book focuses on topics including: abstract parabolic and hyperbolic linear differential equations; nonlinear abstract parabolic equations; holomorphic semigroups; and Volterra operator integral equations.;With contributions from international experts, Differential Equations in Banach Spaces is intended for research mathematicians in functional analysis, partial differential equations, operator theory and control theory; and students in these disciplines.

PREFACE The theory of differential-operator equations has been described in various monographs, but the initial physical problem which leads to these equations is often hidden. When the physical problem is studied, the mathematical proofs are either not given or are quickly explained. In this book, we give a systematic treatment of the partial differential equations which arise in elastostatic problems. In particular, we study problems which are obtained from asymptotic expansion with two scales. Here the methods of operator pencils and differential-operator equations are used. This book is intended for scientists and graduate students in Functional Analy sis, Differential Equations, Equations of Mathematical Physics, and related topics. It would undoubtedly be very useful for mechanics and theoretical physicists. We would like to thank Professors S. Yakubov and S. Kamin for helpfull dis cussions of some parts of the book. The work on the book was also partially supported by the European Community Program RTN-HPRN-CT-2002-00274. xiii INTRODUCTION In first two sections of the introduction, a classical mathematical problem will be exposed: the Laplace problem. The domain of definition will be, on the first time, an infinite strip and on the second time, a sector. To solve this problem, a well known separation of variables method will be used. In this way, the structure of the solution can be explicitly found. For more details about the separation of variables method exposed in this part, the reader can refer to, for example, the book by D. Leguillon and E. Sanchez-Palencia [LS].

The theory of abstract differential equations is a new branch of operator theory and of ordinary differential equations. It is a rapidly developing area of mathematics, and this book presents new results at the forefront of research in this field. Based on the author's own work, this volume covers differential equations in abstract spaces, presenting new and some of the lesser known facts and propositions of the theory. It will be invaluable reading for postgraduate students and research workers in ordinary and partial differential equations, almost-periodic solutions, theory of semigroups of operators and evolution equations.

This book presents results on the geometric/topological structure of the solution set S of an initial-value problem x(t) = f(t, x(t)), x(0) =xo, when f is a continuous function with values in an infinite-dimensional space. A comprehensive survey of existence results and the properties of S, e.g. when S is a connected set, a retract, an acyclic set, is presented. The authors also survey results onthe properties of S for initial-value problems involving differential inclusions, and for boundary-value problems. This book will be of particular interest to researchers in ordinary and partial differential equations and some workers in control theory.