Variational Inequalities and Frictional Contact Problems Variational Inequalities and Frictional Contact Problems contains a carefully selected collection of results on elliptic and evolutionary quasi variational inequalities including existence uniqueness regularity dual formulations numerical approximations and error estimates ones. By using a wide range of methods and arguments the results are presented in a constructive way with clarity and well justified proofs. This approach makes the subjects accessible to mathematicians and applied mathematicians. Moreover this part of the book can be used as an excellent background for the investigation of more general classes of variational inequalities. The abstract variational inequalities considered in this book cover the variational formulations of many static and quasi static contact problems. Based on these abstract results in the last part of the book certain static and quasi static frictional contact problems in elasticity are studied in an almost exhaustive way. The readers will find a systematic and unified exposition on classical variational and dual formulations existence uniqueness and regularity results finite element approximations and related optimal control problems. This part of the book is an update of the Signorini problem with nonlocal Coulomb friction a problem little studied and with few results in the literature. Also in the quasi static case a control problem governed by a bilateral contact problem is studied. Despite the theoretical nature of the presented results the book provides a background for the numerical analysis of contact problems. The materials presented are accessible to both graduate under graduate students and to researchers in applied mathematics mechanics and engineering. The obtained results have numerous applications in mechanics engineering and geophysics. The book contains a good amount of original results which in this unified form cannot be found anywhere else Introduction Part I: Preliminaries Spaces of Real valued Functions Spaces of Vector valued Functions Part II: Variational Inequalities Existence and Uniqueness Results Some Properties of Solutions Dual Formulations Approximations of Variational Inequalities Part III: Contact Problems with Friction in Elasticity Static Problems Quasistatic Problems