This book constitutes the refereed proceedings of the 9th International Conference on Concurrency Theory, CONCUR'98, held in Nice, France, in September 1998.The 35 revised full papers presented were carefully selected from a total of 104 submissions.

Sometimes and not never re-revisited: on branching versus linear time.- Controllers for discrete event systems via morphisms.- Synthesis from knowledge-based specifications.- The regular viewpoint on PA-processes.- Herbrand automata for hardware verification.- Control flow analysis for the ?-calculus.- The tau-laws of fusion.- From higher-order ?-calculus to ?-calculus in the presence of static operators.- Minimality and separation results on asynchronous mobile processes.- Abstract games for infinite state processes.- Alternating refinement relations.- Possible worlds process algebras.- Automata and coinduction (an exercise in coalgebra).- Axioms for real-time logics.- Priority and maximal progress are completely axiomatisable (extended abstract).- Simulation is decidable for one-counter nets.- From rewrite to bisimulation congruences.- Reasoning about asynchronous communication in dynamically evolving object structures.- Modelling IP mobility.- Reduction in TLA.- Detecting deadlocks in concurrent systems.- Unfold/fold transformations of CCP programs.- Type systems for concurrent calculi.- Stochastic process algebras benefits for performance evaluation and challenges.- Algebraic techniques for timed systems.- Probabilistic resource failure in real-time process algebra.- Towards performance evaluation with general distributions in process algebras.- Stochastic transition systems.- It's about time: Real-time logics reviewed.- Controlled timed automata.- On discretization of delays in timed automata and digital circuits.- Partial order reductions for timed systems.- Unfolding and finite prefix for nets with read arcs.- Asynchronous cellular automata and asynchronous automata for pomsets.- Deriving unbounded Petri nets from formal languages.- Decompositions ofasynchronous systems.- Synthesis of ENI-systems using minimal regions.- A categorical axiomatics for bisimulation.- Fibrational semantics of dataflow networks.- A relational model of non-deterministic dataflow.- Checking verifications of protocols and distributed systems by computer.