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Refinement of Actions and Equivalence Notions for Concurrent Systems
 Acta Informatica
, 1998
"... This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, th ..."
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Cited by 59 (3 self)
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This paper combines and extends the material of [GGa/c/d/e], except for the part in [GGc] on refinement of transitions in Petri nets and the discussion of TCSPlike parallel composition in [GGe]. An informal presentation of some basic ingredients of this paper appeared as [GGb]. Among others, the treatment of action refinement in stable and nonstable event structures is new. The research reported here was supported by Esprit project 432 (METEOR), Esprit Basic Research Action 3148 (DEMON), Sonderforschungsbereich 342 of the TU Munchen, ONR grant N0001492J1974 and the Human Capital and Mobility Cooperation Network EXPRESS (Expressiveness of Languages for Concurrency). Contents
Finite equational bases in process algebra: Results and open questions
 Processes, Terms and Cycles: Steps on the Road to Infinity, LNCS 3838
, 2005
"... Abstract. Van Glabbeek (1990) presented the linear time/branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete axiomatizations for them. ..."
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Cited by 31 (21 self)
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Abstract. Van Glabbeek (1990) presented the linear time/branching time spectrum of behavioral equivalences for finitely branching, concrete, sequential processes. He studied these semantics in the setting of the basic process algebra BCCSP, and tried to give finite complete axiomatizations for them. Obtaining such axiomatizations in concurrency theory often turns out to be difficult, even in the setting of simple languages like BCCSP. This has raised a host of open questions that have been the subject of intensive research in recent years. Most of these questions have been settled over BCCSP, either positively by giving a finite complete axiomatization, or negatively by proving that such an axiomatization does not exist. Still some open questions remain. This paper reports on these results, and on the stateoftheart in axiomatizations for richer process algebras with constructs like sequential and parallel composition. 1
Action Refinement
 Handbook of Proacess Algebra
, 2000
"... S. All local authors can be reached via email at the address lastname@cs.unibo.it. Questions and comments should be addressed to tradmin@cs.unibo.it. Recent Titles from the UBLCS Technical Report Series 974 An Algebra of Actors, M. Gaspari, G. Zavattaro, May 1997. 975 On the Turing Equivalen ..."
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Cited by 29 (4 self)
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S. All local authors can be reached via email at the address lastname@cs.unibo.it. Questions and comments should be addressed to tradmin@cs.unibo.it. Recent Titles from the UBLCS Technical Report Series 974 An Algebra of Actors, M. Gaspari, G. Zavattaro, May 1997. 975 On the Turing Equivalence of Linda Coordination Primitives, N. Busi, R. Gorrieri, G. Zavattaro, May 1997 (Revised October 1998). 976 A Process Algebraic View of Linda Coordination Primitives, N. Busi, R. Gorrieri, G. Zavattaro, May 1997. 977 Validating a Software Architecture with respect to an Architectural Style, P. Ciancarini, W. Penzo, July 1997. 978 System Support for PartitionAware Network Applications, O. Babaoglu, R. Davoli, A. Montresor, R. Segala, October 1997. 979 Generalized SemiMarkovian Process Algebra, M. Bravetti, M. Bernardo, R. Gorrieri, October 1997. 981 Group Communication in Partitionable Systems: Specification and Algorithms, O. Babao glu, R. Davoli, A. Montresor, April 1998. 982...
Relationships between Models of Concurrency
, 1994
"... . Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. The ..."
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Cited by 26 (4 self)
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. Models for concurrency can be classified with respect to three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics. The classifications are formalized through the medium of category theory. Keywords. Semantics, Concurrency, Models for Concurrency, Categories. Contents 1 Preliminaries 431 2 Deterministic Transition Systems 433 3 Noninterleaving vs. Interleaving Models 436 Synchronization Trees and Labelled Event Structures : : : : : : : : : : : : : : 438 Transition Systems with Independence : : : : : : : : : : : : : : : : : : : : : : 439 4 Behavioural, Linear Time, Noninterleaving Models 441 Semilanguages and Event Structures : : : : : : : : : : : : : : : : : : : : : : : 443 Trace Languages and Event Structures : : : : : : : : : : : : : : : : : : : : : : 446 5 Transition Systems with Independence and Lab...
Higher Dimensional Automata Revisited
 MATHEMATICAL STRUCTURES IN COMPUTER SCIENCE
, 2000
"... ..."
Asynchronous cellular automata for pomsets
 Theoretical Computer Science
, 1996
"... This paper extends to pomsets without autoconcurrency the fundamental notion of asynchronous cellular automata (ACA) which was originally introduced for traces by Zielonka. We generalize to pomsets the notion of asynchronous mapping introduced by Cori, Métivier and Zielonka and we show how to const ..."
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Cited by 20 (4 self)
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This paper extends to pomsets without autoconcurrency the fundamental notion of asynchronous cellular automata (ACA) which was originally introduced for traces by Zielonka. We generalize to pomsets the notion of asynchronous mapping introduced by Cori, Métivier and Zielonka and we show how to construct a deterministic ACA from an asynchronous mapping. Then we investigate the relation between the expressiveness of monadic second order logic, nondeterministic ACAs and deterministic ACAs. We can generalize Büchi’s theorem for finite words to a class of pomsets without autoconcurrency which satisfy a natural axiom. This axiom ensures that an asynchronous cellular automaton works on the pomset as a concurrent read and exclusive owner write machine. More precisely, in this class nondeterministic ACAs, deterministic ACAs and monadic second order logic have the same expressive power. Then we consider a class where deterministic ACAs are strictly weaker than nondeterministic ones. But in this class nondeterministic ACAs still capture monadic second order logic. Finally it is shown that even this equivalence does not hold in the class of all pomsets since there the class of recognizable pomset languages is not closed under complementation.
CCS with Hennessy’s merge has no finite equational axiomatization
 Theoretical Computer Science
, 2005
"... This paper confirms a conjecture of Bergstra and Klop’s from 1984 by establishing that the process algebra obtained by adding an auxiliary operator proposed by Hennessy in 1981 to the recursion free fragment of Milner’s Calculus of Communicationg Systems is not finitely based modulo bisimulation equ ..."
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Cited by 20 (17 self)
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This paper confirms a conjecture of Bergstra and Klop’s from 1984 by establishing that the process algebra obtained by adding an auxiliary operator proposed by Hennessy in 1981 to the recursion free fragment of Milner’s Calculus of Communicationg Systems is not finitely based modulo bisimulation equivalence. Thus Hennessy’s merge cannot replace the left merge and communication merge operators proposed by Bergstra and Klop, at least if a finite axiomatization of parallel composition is desired.
Pomsets for Message Sequence Charts
 1st Workshop of the SDL Forum Society on SDL and MSC, SAM98
, 1998
"... Message sequence charts (MSCs) are a standardised formalism for the specification of the system's communication behaviour that is widely used by industry. Various extensions to MSCs have recently been standardised by the ITU. This paper treats the extension of MSCs with structural operators tha ..."
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Cited by 19 (0 self)
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Message sequence charts (MSCs) are a standardised formalism for the specification of the system's communication behaviour that is widely used by industry. Various extensions to MSCs have recently been standardised by the ITU. This paper treats the extension of MSCs with structural operators that allow the hierarchical composition of MSCs. In particular, we propose a lineartime partialorder semantics for this extension that is based on the notion of partialorder multisets (pomsets, for short). We provide a compositional denotational semantics for hierarchical MSCs and show that wellknown operations on pomsets correspond to the new composition operators in MSCs. The main benefit of our approach is that the semantics is conceptually rather straightforward, as opposed to the operational semantics for MSCs that is currently in the process of standardisation. Keywords Denotational semantics, partialorder multiset, hierarchical MSC 1 INTRODUCTION In the telecommunication sector, MSC ...
Nested Semantics over Finite Trees are Equationally Hard
, 2003
"... This paper studies nested simulation and nested trace semantics over the language BCCSP, a basic formalism to express finite process behaviour. It is shown that none of these semantics affords finite (in)equational axiomatizations over BCCSP. In particular, for each of the nested semantics studied ..."
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Cited by 15 (12 self)
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This paper studies nested simulation and nested trace semantics over the language BCCSP, a basic formalism to express finite process behaviour. It is shown that none of these semantics affords finite (in)equational axiomatizations over BCCSP. In particular, for each of the nested semantics studied in this paper, the collection of sound, closed (in)equations over a singleton action set is not finitely based.
Transition and cancellation in concurrency and branching time
 Mathematical Structures in Computer Science 13(4) (2003
, 2002
"... We review the conceptual development of (true) concurrency and branching time starting from Petri nets and proceeding via Mazurkiewicz traces, pomsets, bisimulation, and event structures up to higher dimensional automata (HDAs), whose acyclic case may be identified with triadic event structures and ..."
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Cited by 15 (1 self)
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We review the conceptual development of (true) concurrency and branching time starting from Petri nets and proceeding via Mazurkiewicz traces, pomsets, bisimulation, and event structures up to higher dimensional automata (HDAs), whose acyclic case may be identified with triadic event structures and triadic Chu spaces. Acyclic HDAs may be understood as the extension of Boolean logic with a third truth value expressing transition. We prove the necessity of such a third value under mild assumptions about the nature of observable events, and show that the expansion of any complete Boolean basis L to L with a third literal �a expressing a = forms an expressively complete basis for the representation of acyclic HDAs. The main contribution is a new event state × of cancellation, sibling to, serving to distinguish a(b + c) from ab + ac while simplifying the extensional definitions of termination �A and sequence AB. We show that every HDAX (acyclic HDA with ×) is representable in the expansion of L to L × with a fourth literal �a expressing a = ×.