TACS 91 is the first International Conference on Theoretical Aspects of Computer Software, held at Tohoku University, Japan. The 38 contributions to this volume offer a representation of active concerns in the theory of programming by an international group of researchers.

The present volume contains the proceedings of Logic at Botik '89, a symposium on logical foundations of computer science organized by the Program Systems Institute of the USSR Academy of Sciences and held at Pereslavl-Zalessky, USSR, July 3-8, 1989. The scope of the symposium was very broad; the topics of interest were: complexity of formal systems, constructive mathematics in computer science, denotational and operational semantics of programs, descriptive complexity, dynamic and algorithmic logics and schematology, formal tools to describe concurrent computations,...