This is a textbook on program verification. It concentrates on those verification methods that have now become classic such as the inductive assertions method of Floyd, the axiomatic method of Hoare and Scott's fixpoint induction. The aim of the book is to present these different verification methods and to explain their mathemati cal background. The subject is treated with mathematical precision, and many examples are included. Throughout the book the same examples will reappear to illustrate how the different methods are related. The material is self-contained and accessible without prior...