This volume contains the proceedings of STACS 91, a symposium on the theoretical aspects of computer science, held in Hamburg, Germany in February 1991. STACS is held each year, alternately in Germany and France, and is organized jointly by the Special Interest Group for Theoretical Computer Science of the Gesellschaft fuer Informatik (GI) and the Special Interest Group for Applied Mathematics of the Association Francaise des Sciences et Techniques de l'Information et de Systemes (AFCET).

This volume gives the proceedings of the ninth Symposium on Theoretical Aspects of Computer Science (STACS). This annual symposium is held alternately in France and Germany and is organized jointly by the Special Interest Group for Fundamental Computer Science of the Association Francaise des Sciences et Technologies de l'Information et des Syst mes (AFCET) and the Special Interest Group for Theoretical Computer Science of the Gesellschaft f}r Informatik (GI). The volume includes three invited lectures and sections on parallel algorithms, logic and semantics, computational geometry, automata...

This is an anthology of refereed papers arranged to acknowledge the work of Wilfried Brauer on the occasion of his 60th birthday. It contains 49 papers organized in topical sections on computer science and its potential, social implications of computer science, formal languages and automata, structures and complexity theory, Petri nets, systems analysis and distributed systems, software engineering and verification, cognition and artificial intelligence, knowledge representation and reasoning, machine learning, neural networks and robotics, and language and information systems.

Replacement systems, such as term rewriting systems, tree manipulat ing systems, and graph grammars, have been used in Computer Science in the context of theorem proving, program optimization, abstract data types, algebraic simplification, and symbolic comput ation. Replacement systems for strings arose about seventy years earlier in the area of combinatory logic and group theory. The most natural and appropriate formalism for dealing with string rewriting is the notion of a semi-Thue system and this monograph treats its central aspects. The reduction relation is here defined firstly by the...

Replacement systems, such as term rewriting systems, tree manipulat ing systems, and graph grammars, have been used in Computer Science in the context of theorem proving, program optimization, abstract data types, algebraic simplification, and symbolic comput ation. Replacement systems for strings arose about seventy years earlier in the area of combinatory logic and group theory. The most natural and appropriate formalism for dealing with string rewriting is the notion of a semi-Thue system and this monograph treats its central aspects. The reduction relation is here defined firstly by the...