This volume presents the proceedings of the workshop CSL ''91
(Computer


Science Logic) held at the University of Berne,
Switzerland, October 7-11,
1991. This was the fifth in a
series of annual workshops on computer sciencelogic (the
first four are recorded in LNCS volumes 329, 385, 440,




and
533).
The volume contains 33 invited and selected papers on



a
variety of logical topics in computer science, including
abstract datatypes, bounded theories, complexity results,
cut elimination, denotational
semantics, infinitary queries,
Kleene algebra with recursion, minimal


proofs, normal forms
in infinite-valued logic, ordinal processes,




persistent
Petri nets, plausibility logic, program synthesis







systems,
quantifier hierarchies, semantics of modularization,






stable
logic, term rewriting systems, termination of logic
programs,

transitive closure logic, variants of resolution,
and many others.