This volume contains papers which were contributed for presentation at the international conference "Fundamentals of Computation Theory - FCT '91" heldat Gosen, near Berlin, September 9-13, 1991. This was the eighth in the series of FCT conferences organized every odd year. The programme of theconference, including invited lectures and selected contributions, falls into the following categories: - Semantics and logical concepts in the theory of computing, formal specification, - Automata and formal languages, Computational geometry, - Algorithmic aspects of algebra and algebraic geometry, cryptography, - Complexity (sequential, parallel, distributed computing, structure, lower bounds, complexity of analytical problems, general concepts), - Algorithms (efficient, probabilistic, parallel, sequential, distributed), - Counting and combinatorics in connection with mathematical computer science. The proceedings of previous FCT meetings are available as Lecture Notes in Computer Science (Vols. 380, 278, 199, 158, 117, 56).