Marek Galewski – författare

This textbook introduces some basic tools from the theory of monotone operators together with some of their applications. Examples that work  for ordinary differential equations are provided. The illustrating material is kept relatively simple, while at the same time offering inspiring applications to the reader.The material will appeal to graduate students in mathematics who want to learn some basics in the theory of monotone operators. Furthermore, it offers a smooth transition to studying more advanced topics pertaining to more refined applications by shifting to pseudomonotone operators, and next, to multivalued monotone operators.

This textbook gives an introduction to optimization tools which arise around the Weierstrass theorem about the minimum of a lower semicontinuous function. Starting from a Euclidean space, it moves further into the infinite dimensional setting towards the direct variational method, going through differentiation and introducing relevant background information on the way.Exercises accompany the text and include observations, remarks, and examples that help understand the presented material. Although some basic knowledge of functional analysis is assumed, covering Hilbert and Banach spaces and the Lebesgue integration, the required background material is covered throughout the text, and literature suggestions are provided. For less experienced readers, a summary of some optimization techniques is also included.The book will appeal to both students and instructors in specialized courses on optimization, wishing to learn more about variational methods.

This book addresses problems driven by differential operators that lack monotonicity. The authors’ methods rely on coercivity and continuity, allowing for the construction of an approximative scheme whose convergence is induced by coercivity.This observation leads to a new type of solution, which is precisely a limit of finite-dimensional approximation schemes and leads to the weak solution, provided that the operator driving the equation is at least pseudomonotone. This new type of solution is called a generalized solution. To systematically treat its existence, the authors introduce an abstract existence tool that serves as a counterpart to the Browder-Minty Theorem in the non-variational case and the Weierstrass-Tonelli Theorem if the problem is potential. Thus, the authors utilize many already developed techniques, suitably modified due to the absence of the monotonicity assumption.The authors obtain three abstract results, also in the non-smooth case, which they apply to nonlinear boundary value problems. In their applications, they also deal with problems depending on an unbounded weight, which forces them to implement a suitable truncation technique.The book includes an extended chapter covering analysis on abstract tools from the theory of monotone operators and minimization techniques, supplied with proofs and comments that allow for a better understanding of the authors’ approach towards generalized solutions. It includes necessary background on Sobolev spaces, introduces the non-variational generalized solution, and investigates the existence of solutions for variational problems and inclusions.