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Using the PiCalculus for Formalizing Workflow Patterns
 BPM 2005, VOLUME 3649 OF LNCS
, 2005
"... This paper discusses the application of a general process theory—the picalculus—for describing the behavioral perspective of workflow. The picalculus is a process algebra that describes mobile systems. Mobile systems are made up of components that communicate and change their structure as a resu ..."
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Cited by 46 (10 self)
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This paper discusses the application of a general process theory—the picalculus—for describing the behavioral perspective of workflow. The picalculus is a process algebra that describes mobile systems. Mobile systems are made up of components that communicate and change their structure as a result of communication. The ideas behind mobility, communication and change, can also enrich the workflow domain, where flexibility and reaction to change are main drivers. However, it has not yet been evaluated whether the picalculus is actually appropriate to represent the behavioral patterns of workflow. This paper investigates the issue and introduces a collection of workflow patterns formalizations, each with a sound formal definition and execution semantics. The formalizations can be used as a foundation for patternbased workflow execution, reasoning, and simulation as well as a basis for future research on theoretical aspects of workflow.
A Process Calculus for Mobile Ad Hoc Networks
"... Abstract. We present the ωcalculus, a process calculus for formally modeling and reasoning about Mobile Ad Hoc Wireless Networks (MANETs) and their protocols. The ωcalculus naturally captures essential characteristics of MANETs, including the ability of a MANET node to broadcast a message to any o ..."
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Cited by 38 (2 self)
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Abstract. We present the ωcalculus, a process calculus for formally modeling and reasoning about Mobile Ad Hoc Wireless Networks (MANETs) and their protocols. The ωcalculus naturally captures essential characteristics of MANETs, including the ability of a MANET node to broadcast a message to any other node within its physical transmission range (and no others), and to move in and out of the transmission range of other nodes in the network. A key feature of the ωcalculus is the separation of a node’s communication and computational behavior, described by an ωprocess, from the description of its physical transmission range, referred to as an ωprocess interface. Our main technical results are as follows. We give a formal operational semantics of the ωcalculus in terms of labeled transition systems and show that the state reachability problem is decidable for finitecontrol ωprocesses. We also prove that the ωcalculus is a conservative extension of the πcalculus, and that late bisimulation (appropriately lifted from the πcalculus to the ωcalculus) is a congruence. Congruence results are also established for a weak version of late bisimulation, which abstracts away from two types of internal actions: τactions, as in the πcalculus, and µactions, signaling node movement. Finally, we illustrate the practical utility of the calculus by developing and analyzing a formal model of a leaderelection protocol for MANETs. 1
Resource Access and Mobility Control with Dynamic Privileges Acquisition
 In Proc. of ICALP’03, volume 2719 of LNCS
, 2003
"... Klaim is a process language that permits programming distributed systems made up of several mobile components interacting through multiple distributed tuple spaces. ..."
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Cited by 31 (10 self)
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Klaim is a process language that permits programming distributed systems made up of several mobile components interacting through multiple distributed tuple spaces.
Ensuring termination by typability
 In Proceedings of IFIP TCS 2004
, 2004
"... Abstract. A term terminates if all its reduction sequences are of finite length. We show four type systems that ensure termination of welltyped sscalculus processes. The systems are obtained by successive refinements of the types of the simply typed sscalculus. For all (but one of) the type syste ..."
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Cited by 21 (6 self)
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Abstract. A term terminates if all its reduction sequences are of finite length. We show four type systems that ensure termination of welltyped sscalculus processes. The systems are obtained by successive refinements of the types of the simply typed sscalculus. For all (but one of) the type systems we also present upper bounds to the number of steps welltyped processes take to terminate. The termination proofs use techniques from term rewriting systems. We show the usefulness of the type systems on some nontrivial examples: the encodings of primitive recursive functions, the protocol for encoding separate choice in terms of parallel composition, a symbol table implemented as a dynamic chain of cells. 1 Introduction A term terminates if all its reduction sequences are of finite length. As far as programminglanguages are concerned, termination means that computation in programs will eventually stop. In computer science termination has been extensively investigated in term rewritingsystems [7, 5] and *calculi [9, 4] (where strong normalization is a synonym more commonlyused). Termination has also been discussed in process calculi, notably the
PSICALCULI: A FRAMEWORK FOR MOBILE PROCESSES WITH NOMINAL DATA AND LOGIC
"... Abstract. The framework of psicalculi extends the picalculus with nominal datatypes for data structures and for logical assertions and conditions. These can be transmitted between processes and their names can be statically scoped as in the standard picalculus. Psicalculi can capture the same ph ..."
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Cited by 20 (6 self)
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Abstract. The framework of psicalculi extends the picalculus with nominal datatypes for data structures and for logical assertions and conditions. These can be transmitted between processes and their names can be statically scoped as in the standard picalculus. Psicalculi can capture the same phenomena as other proposed extensions of the picalculus such as the applied picalculus, the spicalculus, the fusion calculus, the concurrent constraint picalculus, and calculi with polyadic communication channels or pattern matching. Psicalculi can be even more general, for example by allowing structured channels, higherorder formalisms such as the lambda calculus for data structures, and predicate logic for assertions. We provide ample comparisons to related calculi and discuss a few significant applications. Our labelled operational semantics and definition of bisimulation is straightforward, without a structural congruence. We establish minimal requirements on the nominal data and logic in order to prove general algebraic properties of psicalculi, all of which have been checked in the interactive theorem prover Isabelle. Expressiveness of psicalculi significantly exceeds that of other formalisms, while the purity of the semantics is on par with the original picalculus. 1.
A formal calculus for informal equality with binding
 In WoLLIC’07: 14th Workshop on Logic, Language, Information and Computation, volume 4576 of LNCS
, 2007
"... Abstract. In informal mathematical usage we often reason using languages with binding. We usually find ourselves placing captureavoidance constraints on where variables can and cannot occur free. We describe a logical derivation system which allows a direct formalisation of such assertions, along w ..."
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Cited by 18 (6 self)
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Abstract. In informal mathematical usage we often reason using languages with binding. We usually find ourselves placing captureavoidance constraints on where variables can and cannot occur free. We describe a logical derivation system which allows a direct formalisation of such assertions, along with a direct formalisation of their constraints. We base our logic on equality, probably the simplest available judgement form. In spite of this, we can axiomatise systems of logic and computation such as firstorder logic or the lambdacalculus in a very direct and natural way. We investigate the theory of derivations, prove a suitable semantics sound and complete, and discuss existing and future research. 1
A congruence format for namepassing calculi
 In Proceedings of the Second Workshop on Structural Operational Semantics (SOS’05), volume 156 of Electron. Notes Theor. Comput. Sci
, 2005
"... ..."
On the relative expressive power of asynchronous communication primitives
 Proceedings of 9th International Conference on Foundations of Software Science and Computation Structures (FoSSaCS’06), volume 3921 of Lecture Notes in Computer Science
, 2006
"... Abstract. In this paper, we study eight asynchronous communication primitives, arising from the combination of three features: arity (monadic vs polyadic data), communication medium (message passing vs shared dataspaces) and patternmatching. Each primitive has been already used in at least one langu ..."
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Cited by 16 (5 self)
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Abstract. In this paper, we study eight asynchronous communication primitives, arising from the combination of three features: arity (monadic vs polyadic data), communication medium (message passing vs shared dataspaces) and patternmatching. Each primitive has been already used in at least one language appeared in literature; however, to uniformly reason on such primitives, we plugged them in a common framework inspired by the asynchronous ¢calculus. By means of possibility/impossibility of ‘reasonable ’ encodings, we compare every pair of primitives to obtain a hierarchy of languages based on their relative expressive power. 1
On the Expressive Power of Klaimbased Calculi.
 Research report, Dipartimento di Sistemi e Informatica, Universita di Firenze,
, 2004
"... Abstract In this work, we study the expressive power of variants of Klaim, an experimental language with programming primitives for global computing that combines the process algebra approach with the coordinationoriented one. Klaim has proved to be suitable for programming a wide range of distrib ..."
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Cited by 16 (9 self)
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Abstract In this work, we study the expressive power of variants of Klaim, an experimental language with programming primitives for global computing that combines the process algebra approach with the coordinationoriented one. Klaim has proved to be suitable for programming a wide range of distributed applications with agents and code mobility, and has been implemented on the top of a runtime system based on Java. The expressivity of its constructs is tested by distilling from it some (more and more foundational) calculi and studying the encoding of each of the considered languages into a simpler one. An encoding of the asynchronous πcalculus into one of these calculi is also presented.
Basic Observables for a Calculus for Global Computing
, 2004
"... We develop the semantic theory of a foundational language for modelling applications over global computers whose interconnection structure can be explicitly manipulated. Together with process distribution, process mobility and remote asynchronous communication through distributed data repositories, ..."
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Cited by 15 (8 self)
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We develop the semantic theory of a foundational language for modelling applications over global computers whose interconnection structure can be explicitly manipulated. Together with process distribution, process mobility and remote asynchronous communication through distributed data repositories, the language provides constructs for explicitly modelling internode connections and for dynamically activating and deactivating them. For the proposed language, we define natural notions of extensional observations and study their closure under operational reductions and/or language contexts to obtain barbed congruence and may testing equivalence. For such equivalences, we provide alternative characterizations in terms of a labelled bisimulation and a trace equivalence that can be used for actual proofs. We discuss how the language and its theory can be extended to include more sophisticated features that enable a finer control on the activation of connections. To asses practical usability of the semantic theory, we model a scenario for communications between mobile devices and use the introduced proof techniques to analyze it and verify some relevant properties.