Compositional Constructor Interpretation over Coalgebraic Models for the π—Calculus

AbstractThe π-calculus and its variants are one of the most important subjects in the field of process algebra. Researchers in the coalgebra community have taken account of that by developing a family of related final coalgebra models for the π-calculus. None of these models has, however, been given with interpretations of the π-calculus constructors as operations on semantic domains. The present paper introduces such interpretations over final coalgebra models for the π-calculus. These models do not exactly belong to the realm of the already existing work. Rather, we emphasise the distinction between a a ground model and a full model: The ground model is fully abstract with respect to a form of π-calculus ground bisimulation; the full model is built on top of the ground model and is fully abstract with respect to the congruence derived from that ground bisimulation. Also, every semantic object is a 3-tuple with a direct representation of its transformation under renamings. A straightforward adaption of Rutten and Turi's mixed terms technique then yields compositional interpretations of most constructors of the π-calculus on the ground level. These interpretations can be lifted to the full level, again yielding compositionality.Because input prefixing does not preserve ground bisimilarity, this π-calculus constructor cannot be interpreted compositionally strictly on the ground level. It is therefore given an independent interpretation over the full model

Web Services as a New Approach to Distributing and Coordinating Semantics-Based Veri cation Toolkits

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The "Rights Awakening" of Chinese Migrant Workers: Beyond the Generational Perspective

In the spring of 2010, the strike of the Honda workers in Nanhai instigated an on-going discourse on the rights awakening of the new generation of migrant workers. Since then, much has been written about these young workers, generally described as more pro-active and ready to stand up against their employers than the older and more subservient generation. Drawing from statistical findings from two factory-gate surveys in the metal mechanics and garment sectors in Shenzhen, this paper tests two hypotheses: (a) that workers of the younger generation are more cognizant of their legal rights than older workers; (b) that the younger generation wants to work fewer hours and to enjoy life more. We argue that this popular image of the younger generation of migrant workers is one-dimensional and reductive, as it focuses only on generational differences as an explanatory factor for worker activism, while ignoring other issues such as types of industries and payment systems. In this paper, we purport that these elements play important roles in shaping the attitude of this younger generation toward their work and rights

Class dynamics of development: a methodological note

This article argues that class relations are constitutive of developmental processes and central to understanding inequality within and between countries. In doing so it illustrates and explains the diversity of the actually existing forms of class relations, and the ways in which they interplay with other social relations such as gender and ethnicity. This is part of a wider project to re- vitalise class analysis in the study of development problems and experiences

CCS without r's with Built-in Service Rendezvous

We introduce a pure process calculus and a value--passing process calculus in which the discipline of process interaction is not, as usual, the synchronous execution of actions but the service rendezvous (rendezvous). New is the following combination: (1) The rendezvous is a primitive. I.e. every particular rendezvous requires exactly one explicit synchronization between the processes taking part in it, namely at its beginning. In this way the framework to be presented here reflects the situation prevailing in many programming languages where the rendezvous is built--in. Such languages are Ada ([DoD83]), Egger's AP ([Egg91]), and POOL ([Ame87]). (2) There is no operator for sequential composition. As a consequence the value passing calculus can be defined in a way so that it is as integrated as, for example, value--passing CCS. In earlier accounts of the rendezvous to which (1) applies we have the situation that (2) does not. The non--pure formalisms in these frameworks exhibit a divis..

A Non-well-founded Sets Semantics for Observation Congruence over Full CCS

. In the present paper we study the semantics of a minor variant of Milner's CCS process calculus. We use a compact semantic domain for processes which has been described by Aczel in [P. Aczel. Non--well--founded Sets. Stanford University, 1988.] On the basis of the operational semantics of CCS we construct a semantic mapping from CCS into the domain. We prove that this mapping is fully abstract wrt. observation congruence, initial in a category of algebras, and final in a category of coalgebras. Furthermore, we give a logical characterization of the objects reached by it. 1. Introduction Observation congruence ([Mil80], [Mil89]) has become one of the most successful concepts in process algebra. It is the coarsest congruence contained in weak bisimulation equivalence, an equivalence which abstracts from invisible behaviour and is thus very intuitive. What is more, observation congruence usually differs from weak bisimulation equivalence only in the treatment of initial invisible tran..

Adding Enrichments to Refined Interleavings: A New Model for the π-Calculus

The question of how to model π-calculus name passing has attracted significant interest. Here, this topic is approached with a new fully abstract interleaving model. Its central feature: Every semantic object contains all its transformations under injective name replacements. It is shown how this enrichment can be used, in a systematic way, to obtain compositional interpretations of the constructors of the π-calculus. The theory of non-well-founded sets serves as the mathematical basis. Moreover, category theory is used in the form of coalgebras of endo-functors. Not more is needed since transformations under name replacements are not regarded as arrows of a category of partial orders of (un-enriched) semantic objects. This approach is a hallmark of previous interleaving models of the π-calculus. It seems to require a lot more category theory than is used here. Also, unlike other related work, the present one does not employ type theory