Several types of differential equations, such as functional differential equation, age-structured models, transport equations, reaction-diffusion equations, and partial differential equations with delay, can be formulated as abstract Cauchy problems with non-dense domain. This monograph provides a self-contained and comprehensive presentation of the fundamental theory of non-densely defined semilinear Cauchy problems and their applications. Starting from the classical Hille-Yosida theorem, semigroup method, and spectral theory, this monograph introduces the abstract Cauchy problems with non-dense domain, integrated semigroups, the existence of integrated solutions, positivity of solutions, Lipschitz perturbation, differentiability of solutions with respect to the state variable, and time differentiability of solutions. Combining the functional analysis method and bifurcation approach in dynamical systems, then the nonlinear dynamics such as the stability of equilibria, center manifoldtheory, Hopf bifurcation, and normal form theory are established for abstract Cauchy problems with non-dense domain. Finally applications to functional differential equations, age-structured models, and parabolic equations are presented. This monograph will be very valuable for graduate students and researchers in the fields of abstract Cauchy problems, infinite dimensional dynamical systems, and their applications in biological, chemical, medical, and physical problems.

Dr. Pierre Magal is a professor in the Institut de Mathématiques de Bordeaux at the University of Bordeaux, France. His research interests are Differential Equations, Dynamical Systems, and Mathematical Biology. He studies nonlinear dynamics of abstract semilinear equations, functional differential equations, age-structured models, and parabolic systems. He is also interested in modeling some biological, epidemiological, and medical problems and studying the nonlinear dynamics of these models.

Shigui Ruan is a professor in the Department of Mathematics at the University of Miami, Coral Gables, Florida, USA. His research interests are Differential Equations, Dynamical Systems, and Mathematical Biology. He studies nonlinear dynamics of some types of differential equations, such as the center manifold theory and Hopf bifurcation in semilinear evolution equations, multiple-parameter bifurcations in delay equations, and traveling waves in nonlocal reaction-diffusion systems. He is also interested in modeling and studying transmission dynamics of some infectious diseases (malaria, Rift Valley Fever, Hepatitis B virus, schistosomiasis, human rabies, SARS, West Nile virus, etc.) and nonlinear population dynamics.

Chapter 1- Introduction.- Chapter 2- Semigroups and Hille-Yosida Theorem.- Chapter 3- Integrated Semigroups and Cauchy Problems with Non-dense Domain.- Chapter 4- Spectral Theory for Linear Operators.- Chapter 5- Semilinear Cauchy Problems with Non-dense Domain.- Chapter 6- Center Manifolds, Hopf Bifurcation and Normal Forms.- Chapter 7- Functional Differential Equations.- Chapter 8- Age-structured Models.- Chapter 9- Parabolic Equations.- References.- Index.