A complete axiomatisation for observational congruence of finite-state behaviours
Information and Computation
Priorities in process algebras
Information and Computation - Selections from 1988 IEEE symposium on logic in computer science
Information and Computation
Modeling and verification of randomized distributed real-time systems
Modeling and verification of randomized distributed real-time systems
Communication and Concurrency
Quantitative information in the tuple space coordination model
Theoretical Computer Science - Quantitative aspects of programming languages (QAPL 2004)
Observing Branching Structure through Probabilistic Contexts
SIAM Journal on Computing
Probabilistic embedding: experiments with tuple-based probabilistic languages
Proceedings of the 28th Annual ACM Symposium on Applied Computing
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Defining operational semantics for a process algebra is often based either on labeled transition systems that account for interaction with a context or on the so-called reduction semantics: we assume to have a representation of the whole system and we compute unlabeled reduction transitions (leading to a distribution over states in the probabilistic case). In this paper we consider mixed models with states where the system is still open (towards interaction with a context) and states where the system is already closed. The idea is that (open) parts of a system ''P'' can be closed via an operator ''P@6G'' that turns already synchronized actions whose ''handle'' is specified inside ''G'' into prioritized reduction transitions (and, therefore, states performing them into closed states). We show that we can use the operator ''P@6G'' to express multi-level priorities and external probabilistic choices (by assigning weights to handles inside G), and that, by considering reduction transitions as the only unobservable @t transitions, the proposed technique is compatible, for process algebra with general recursion, with both standard (probabilistic) observational congruence and a notion of equivalence which aggregates reduction transitions in a (much more aggregating) trace based manner. We also observe that the trace-based aggregated transition system can be obtained directly in operational semantics and we present the ''aggregating'' semantics. Finally, we discuss how the open/closed approach can be used to also express discrete and continuous (exponential probabilistic) time and we show that, in such timed contexts, the trace-based equivalence can aggregate more with respect to traditional lumping based equivalences over Markov Chains.