At least four research fields detennine the theoretical background of specification and deduction in computer science: recursion theory, automated theorem proving, abstract data types and tenn rewriting systems. As these areas approach each other more and more, the strong distinctions between functional and relational views, deductive and denotational approaches as well as between specification and programming are relieved in favour of their integration. The book will not expose the lines of this development; conversely, it starts out from the nucleus of Hom clause logic and brings forth both known and unknown results, most of which affect more than one of the fields mentioned above. Chapter 1 touches on historical issues of specification and prototyping and delimits the topics handled in this book from others which are at the core of related work. Chapter 2 provides the fundamental notions and notations needed for the presentation and interpretation of many-sorted Horn clause theories with equality. Chapter 3 supplies a number of sample Hom clause specifications ranging from arithmetic through string manipulation to higher data structures and interpreters of programming languages. Some of these examples serve as a reference to illustrate definitions and results, others may throw a light on the strong link between specifications and programs, which are executed by applying deduction rules. Thus we have included examples of how to use program trans/ormation methods in specification design.

Declarative programs consist of mathematical functions and relations and are amenable to formal specification and verification, since the methods of logic and proof can be applied to the programs in a well-defined manner. Here Dr Padawitz emphasizes verification based on logical inference rules, i.e. deduction (in contrast with model-theoretic approaches, deductive methods can be automated to some extent). His treatment of the subject differs from others in that he tries to capture the actual styles and applications of programming; neither too general with respect to the underlying logic, nor too restrictive for the practice of programming. He generalizes and unifies results from classical theorem-proving and term rewriting to provide proof methods tailored to declarative program synthesis and verification. Detailed examples accompany the development of the methods, whose use is supported by a documented prototyping system. The book can be used for graduate courses or as a reference for researchers in formal methods, theorem-proving and declarative languages.