During the past decade, the a posteriori error analysis of numerical methods for partial differential equations has gained a lot of attention as documented by a series of monographs on this subject. There are various techniques including residual and hierarchical type estimators, those which are based on local averaging, and the so-called goal oriented weigthed dual method. The monograph under consideration contains a comprehensive treatment of yet another approach: duality error majorants. These are functional type a posteriori error estimators that result in computable error bounds for all types of conforming approximations.
The monograph provides all necessary prerequisites from the calculus of variations and concentrates on linear and some nonlinear variational problems including second and fourth order elliptic boundary value problems in the linear regime and stationary variational inequalities in the nonlinear case. The book is very well written and technically sound. It should not be missed on the bookshelves of those interested in modern methods for the numerical solution of partial differential equations.