Concurrency cannot be observed, asynchronously†

The paper is devoted to an analysis of the concurrent features of asynchronous systems. A preliminary step is represented by the introduction of a non-interleaving extension of barbed equivalence. This notion is then exploited in order to prove that concurrency cannot be observed through asynchronous interactions, i.e., that the interleaving and concurrent versions of a suitable asynchronous weak equivalence actually coincide. The theory is validated on some case studies, related to nominal calculi (π-calculus) and visual specification formalisms (Petri nets). Additionally, we prove that a class of systems which is deemed (output-buffered) asynchronous, according to a characterization that was previously proposed in the literature, falls into our theory.

[1]  Reiko Heckel,et al.  Graph Grammars with Negative Application Conditions , 1996, Fundam. Informaticae.

[2]  Rob J. van Glabbeek,et al.  The Linear Time - Branching Time Spectrum II , 1993, CONCUR.

[3]  Robin Milner,et al.  Barbed Bisimulation , 1992, ICALP.

[4]  Marco Pistore,et al.  Concurrent Semantics for the π-calculus1 1Work supported in part by Esprit Basic Research project CONFER and working group COMPUGRAPH II and by Progetto Speciale CNR “Specifica ad Alto Livelloe Verifica Formale di Sistemi Digitali”. , 1995 .

[5]  Francesco Zappa Nardelli,et al.  Bisimulation Proof Methods for Mobile Ambients , 2003, ICALP.

[6]  Tilak Agerwala,et al.  Comments on capabilities, limitations and “correctness” of Petri nets , 1973, ISCA 1973.

[7]  Jan A. Bergstra,et al.  Process Algebra with Asynchronous Communication Mechanisms , 1984, Seminar on Concurrency.

[8]  Reiko Heckel,et al.  Compositional semantics for open Petri nets based on deterministic processes , 2005, Mathematical Structures in Computer Science.

[9]  Philippe Darondeau,et al.  Causal Trees , 1989, ICALP.

[10]  Ursula Goltz,et al.  Equivalence Notions for Concurrent Systems and Refinement of Actions (Extended Abstract) , 1989, MFCS.

[11]  Fabio Gadducci,et al.  Encoding Asynchronous Interactions Using Open Petri Nets , 2009, CONCUR.

[12]  Robin Milner,et al.  Communication and concurrency , 1989, PHI Series in computer science.

[13]  Mario Tokoro,et al.  An Object Calculus for Asynchronous Communication , 1991, ECOOP.

[14]  Ekkart Kindler,et al.  A Compositional Partial Order Semantics for Petri Net Components , 1997, ICATPN.

[15]  Davide Sangiorgi,et al.  Some Congruence Properties for Pi-Calculus Bisimilarities , 1998, Theor. Comput. Sci..

[16]  Peter Selinger,et al.  First-Order Axioms for Asynchrony , 1997, CONCUR.

[17]  Robin Milner,et al.  Bigraphs for Petri Nets , 2003, Lectures on Concurrency and Petri Nets.

[18]  Fabio Gadducci,et al.  On Barbs and Labels in Reactive Systems , 2010, SOS.

[19]  Rocco De Nicola,et al.  Partial orderings descriptions and observations of nondeterministic concurrent processes , 1988, REX Workshop.

[20]  Davide Sangiorgi,et al.  On Bisimulations for the Asynchronous pi-Calculus , 1996, Theor. Comput. Sci..

[21]  Daniele Gorla,et al.  Towards a unified approach to encodability and separation results for process calculi , 2008, Inf. Comput..

[22]  Catuscia Palamidessi,et al.  Comparing the expressive power of the synchronous and asynchronous $pi$-calculi , 2003, Mathematical Structures in Computer Science.

[23]  Luca Cardelli,et al.  Mobile Ambients , 1998, FoSSaCS.

[24]  Roberto Bruni,et al.  Event Structure Semantics for Dynamic Graph Grammars , 2006, Electron. Commun. Eur. Assoc. Softw. Sci. Technol..

[25]  Iain Phillips,et al.  CCS with priority guards , 2001, J. Log. Algebraic Methods Program..

[26]  Cédric Fournet,et al.  The reflexive CHAM and the join-calculus , 1996, POPL '96.

[27]  Robin Milner,et al.  Communicating and mobile systems - the Pi-calculus , 1999 .

[28]  Ivan Lanese,et al.  Concurrent and Located Synchronizations in pi-Calculus , 2007, SOFSEM.

[29]  Matthew Hennessy,et al.  Observing Localities , 1993, Theor. Comput. Sci..

[30]  Ursula Goltz,et al.  Symmetric and Asymmetric Asynchronous Interaction , 2008, ICE@ICALP.

[31]  Nobuko Yoshida,et al.  On Reduction-Based Process Semantics , 1995, Theor. Comput. Sci..

[32]  Vladimiro Sassone,et al.  A Congruence for Petri Nets , 2005, PNGT@ICGT.

[33]  Daniele Varacca,et al.  Compositional Event Structure Semantics for the Internal pi -Calculus , 2007, CONCUR.

[34]  Julian Rathke,et al.  Semantic Barbs and Biorthogonality , 2007, FoSSaCS.

[35]  Robin Milner,et al.  Deriving Bisimulation Congruences for Reactive Systems , 2000, CONCUR.

[36]  Frank D. Valencia,et al.  On the Asynchronous Nature of the Asynchronous pi-Calculus , 2008, Concurrency, Graphs and Models.

[37]  Cédric Fournet,et al.  A hierarchy of equivalences for asynchronous calculi , 1998, J. Log. Algebraic Methods Program..

[38]  Fabio Gadducci,et al.  Concurrency Can't Be Observed, Asynchronously , 2010, APLAS.

[39]  Rob J. van Glabbeek,et al.  Petri Net Models for Algebraic Theories of Concurrency , 1987, PARLE.

[40]  Frank S. de Boer,et al.  Asynchronous communication in process algebra , 1992, [1992] Proceedings of the Seventh Annual IEEE Symposium on Logic in Computer Science.

[41]  Roberto Gorrieri,et al.  A Petri Net Semantics for pi-Calculus , 1995, CONCUR.

[42]  Roberto Gorrieri,et al.  Comparing three semantics for Linda-like languages , 2000, Theor. Comput. Sci..