For some years, specification of software and hardware systems has been influenced not only by algebraic methods but also by new developments in logic. These new developments in logic are partly based on the use of algorithmic techniques in deduction and proving methods, but are alsodue to new theoretical advances, to a great extent stimulated by computer science, which have led to new types of logic and new logical calculi. The new techniques, methods and tools from logic, combined with algebra-based ones, offer very powerful and useful tools for the computer scientist, which may soon become practical for commercial use, where, in particular, more powerful specification tools are needed for concurrent and distributed systems. This volume contains papers based on lectures by leading researchers which were originally given at an international summer school held in Marktoberdorf in 1991. The papers aim to give a foundation for combining logic and algebra for the purposes of specification under the aspects of automated deduction, proving techniques, concurrency and logic, abstract data types and operational semantics, and constructive methods.