This open access book presents a comprehensive survey of modern operator techniques for boundary value problems and spectral theory, employing abstract boundary

This book presents a unified theory of the Finite Element Method and the Boundary Element Method for a numerical solution of second order elliptic boundary valu

Presented in this volume are a number of new results concerning the extension theory and spectral theory of unbounded operators using the recent notions of boun

Elliptic boundary problems have enjoyed interest recently, espe cially among C* -algebraists and mathematical physicists who want to understand single aspects o

This book introduces the method of lower and upper solutions for ordinary differential equations. This method is known to be both easy and powerful to solve sec