The specification and verification of communicating systems has captured increasing interest in the last decades. CCS, a Calculus of Communicating Systems [Milner 89a], was especially designed to help this enterprise; it is widely used in both industry and academia. Most efforts to automate the use of CCS for verification have centered around the explicit construction of a bisimulation [Park 81]. This approach, however, presents severe limitations to deal with systems that contain infinite states (e.g. systems with evolving structure [Milner 89a] or that comprise a finite but arbitrary number of components (e.g. systems with inductive structure [Milner 89a]). There is an alternative approach to verification, based on equational reasoning, which does not exhibit such limitations. This formulation, however, introduces significant proof search control issues, and, hence, has remained far less explored. This thesis investigates the use of explicit proof plans [Bundy 88] for problems of automatic verification in the context of CCS. We have conducted the verification task using equational reasoning, and centred on infinite state systems, and parameterised systems. A parameterised system, e.g. a system with inductive structure, circumscribes a family of CCS systems, which have fixed struture and finitely many states. To reason about theses systems, we have adopted Robin Milner's approach [Milner 89a], which advocates the use of induction to exploit the structure and/or the behavior of a system during its verification. To automate this reasoning, wehave used proof plans for induction [Bundy 88]- built within CLAM [Bundy et al 90b], and extended it with special CCS proof plans. We have implemented a verification planner by adding these special proof plans to CLAM. The system handles the search control problems prompted by CCS verification satisfactorily, though it is not complete. Moreover, the system is capable of dealing with the verification of finite state systems, infinite state systems, and parameterised systems, hence, providing a uniform method to analyse CCS systems, regardless of their state space. Our results are encouraging: the verification planner has been successfully tested on a number of examples drawn from the litereature. We have planned proofs of conjectures that are outside the domain of existing verification methods. Furthernore; the verification planning is fully automated. Because of this, even though the verification plan has still got plenty of room for improvement, we can state that proof planning can handle the equational verication of CCS systems, and, therefore, advocate its use within this interesting field.

<p>In a broader sense the main research objective of this thesis (and ongoing research work) is distributed knowledge management for mobile dynamic systems. But the primary focus and presented work focuses on communication/interoperability of heterogeneous entities in an infrastructure less paradigm, a distributed resource manipulation infrastructure and distributed learning in the absence of global knowledge. The research objectives achieved discover the design aspects of heterogeneous distributed knowledge systems towards establishing a seamless integration. This thesis doesn’t cover all aspects in this work; rather focuses on interoperability and distributed learning.</p><p>Firstly a discussion on the issues in knowledge management for swarm of heterogeneous entities is presented. This is done in a broader and rather abstract fashion to provide an insight of motivation for interoperability and distributed learning towards knowledge management. Moreover this will also serve the reader to understand the ongoing work and research activities in much broader perspective.</p><p>Primary focus of this thesis is communication/interoperability of heterogeneous entities in an infrastructure less paradigm, a distributed resource manipulation infrastructure and distributed learning in the absence of global knowledge. In dynamic environments for mobile autonomous systems such as robot swarms or mobile software agents there is a need for autonomic publishing and discovery of resources and just-in-time integration for on-the-fly service consumption without any a priori knowledge. SOA (Service-Oriented Architecture) serves the purpose of resource reuse and sharing of services different entities. Web services (a SOA manifestation) achieves these objectives but its exploitation in dynamic environments, where the communication infrastructure is lacking, requires a considerable research. Generally Web services are exploited in stable client-server paradigms, which is a pressing assumption when dynamic distributed systems are considered. UDDI (Universal Description Discovery and Integration) is the main pediment in the exploitation of Web services in distributed control and dynamic natured systems. UDDI can be considered as a directory for publication and discovery of categorized Web services but assumes a centralized registry; even if distributed registries and associated mechanism are employed problems of collaborative communication in infrastructure less paradigms are ignored.</p><p>Towards interoperability main contribution this thesis is a mediator-based distributed Web services discovery and invocation middleware, which provides a collaborative and decentralized services discovery and management middleware for infrastructure-less mobile dynamic systems with heterogeneous communication capabilities. Heterogeneity of communication capabilities is abstracted in middleware by a conceptual classification of computing entities on the basis of their communication capabilities and communication issues are resolved via conceptual overlay formation for query propagation in system.</p><p>The proposed and developed middleware has not only been evaluated extensively using Player Stage simulator but also been applied in physical robot swarms. Experimental validations analyze the results in different communication modes i. active and ii. passive mode of communication with and without shared resource conflict resolution. I analyze discoverable Web services with respect to time, services available in complete view of cluster and the impact and resultant improvements in distributed Web services discovery by using caching and semantics.</p><p>Second part of this thesis focuses on distributed learning in the absence of global information. This thesis takes the argument of defeasibility (common-sense inference) as the basis of intelligence in human-beings, in which conclusions/inferences are drawn and refuted at the same time as more information becomes available. The ability of common-sense reasoning to adapt to dynamic environments and reasoning with uncertainty in the absence of global information seems to be best fit for distributed learning for dynamic systems.</p><p>This thesis, thus, overviews epistemic cognition in human beings, which motivates the need of a similar epistemic cognitive solution in fabricated systems and considers formal concept analysis as a case for incremental and distributed learning of formal concepts. Thesis also presents a representational schema for underlying logic formalism and formal concepts. An algorithm for incremental learning and its use-case for robotic navigation, in which robots incrementally learn formal concepts and perform common-sense reasoning for their intelligent navigation, is also presented. Moreover elaboration of the logic formalism employed and details of implementation of developed defeasible reasoning engine is given in the latter half of this thesis.</p><p>In summary, the research results and achievements described in this thesis focus on interoperability and distributed learning for heterogeneous distributed knowledge systems which contributes towards establishing a seamless integration in mobile dynamic systems.</p> / QC 20100614 / ROBOSWARM EU FP6

In a broader sense the main research objective of this thesis (and ongoing research work) is distributed knowledge management for mobile dynamic systems. But the primary focus and presented work focuses on communication/interoperability of heterogeneous entities in an infrastructure less paradigm, a distributed resource manipulation infrastructure and distributed learning in the absence of global knowledge. The research objectives achieved discover the design aspects of heterogeneous distributed knowledge systems towards establishing a seamless integration. This thesis doesn’t cover all aspects in this work; rather focuses on interoperability and distributed learning. Firstly a discussion on the issues in knowledge management for swarm of heterogeneous entities is presented. This is done in a broader and rather abstract fashion to provide an insight of motivation for interoperability and distributed learning towards knowledge management. Moreover this will also serve the reader to understand the ongoing work and research activities in much broader perspective. Primary focus of this thesis is communication/interoperability of heterogeneous entities in an infrastructure less paradigm, a distributed resource manipulation infrastructure and distributed learning in the absence of global knowledge. In dynamic environments for mobile autonomous systems such as robot swarms or mobile software agents there is a need for autonomic publishing and discovery of resources and just-in-time integration for on-the-fly service consumption without any a priori knowledge. SOA (Service-Oriented Architecture) serves the purpose of resource reuse and sharing of services different entities. Web services (a SOA manifestation) achieves these objectives but its exploitation in dynamic environments, where the communication infrastructure is lacking, requires a considerable research. Generally Web services are exploited in stable client-server paradigms, which is a pressing assumption when dynamic distributed systems are considered. UDDI (Universal Description Discovery and Integration) is the main pediment in the exploitation of Web services in distributed control and dynamic natured systems. UDDI can be considered as a directory for publication and discovery of categorized Web services but assumes a centralized registry; even if distributed registries and associated mechanism are employed problems of collaborative communication in infrastructure less paradigms are ignored. Towards interoperability main contribution this thesis is a mediator-based distributed Web services discovery and invocation middleware, which provides a collaborative and decentralized services discovery and management middleware for infrastructure-less mobile dynamic systems with heterogeneous communication capabilities. Heterogeneity of communication capabilities is abstracted in middleware by a conceptual classification of computing entities on the basis of their communication capabilities and communication issues are resolved via conceptual overlay formation for query propagation in system. The proposed and developed middleware has not only been evaluated extensively using Player Stage simulator but also been applied in physical robot swarms. Experimental validations analyze the results in different communication modes i. active and ii. passive mode of communication with and without shared resource conflict resolution. I analyze discoverable Web services with respect to time, services available in complete view of cluster and the impact and resultant improvements in distributed Web services discovery by using caching and semantics. Second part of this thesis focuses on distributed learning in the absence of global information. This thesis takes the argument of defeasibility (common-sense inference) as the basis of intelligence in human-beings, in which conclusions/inferences are drawn and refuted at the same time as more information becomes available. The ability of common-sense reasoning to adapt to dynamic environments and reasoning with uncertainty in the absence of global information seems to be best fit for distributed learning for dynamic systems. This thesis, thus, overviews epistemic cognition in human beings, which motivates the need of a similar epistemic cognitive solution in fabricated systems and considers formal concept analysis as a case for incremental and distributed learning of formal concepts. Thesis also presents a representational schema for underlying logic formalism and formal concepts. An algorithm for incremental learning and its use-case for robotic navigation, in which robots incrementally learn formal concepts and perform common-sense reasoning for their intelligent navigation, is also presented. Moreover elaboration of the logic formalism employed and details of implementation of developed defeasible reasoning engine is given in the latter half of this thesis. In summary, the research results and achievements described in this thesis focus on interoperability and distributed learning for heterogeneous distributed knowledge systems which contributes towards establishing a seamless integration in mobile dynamic systems. / QC 20100614 / ROBOSWARM EU FP6

This thesis discusses linguistic constraints on scrambling and flexibility in word order in spoken Persian (Farsi) and presents a computational model for efficient implementation of these constraints for a subset of Persian. Linguistic phenomena which we have studies include local scrambling, long distance scrambling, extrapolation of clauses, topicalisation, case tendancy and the discourse marker ra. The work extends previous work on Persian based on Government and Binding (GB) theory by considering the pragmatic aspects of Persian Grammar and long distance scrambling.

Nous proposons de concevoir et de mettre en oeuvre un environnement logiciel pour une "gestion guidée par les modèles" des changements dans les architectures des applications distribuées coopératives. Les aspects adaptabilité des applications, les aspects transformations de graphe et les aspects particuliers des applications distribuées coopératives sont étudiés. Une approche d'adaptation s'appuyant sur une modélisation par les graphes et un style architectural de type Poducteur/Consommateur est présentée pour des applications communicantes collaboratives sensibles au contexte. Une démarche de raffinement est proposée permettant de garantir un certain degré d'adaptabilité en faisant un compromis entre les différents paramètres du contexte. Ces travaux de recherche ont aussi permis de définir un cadre algorithmique générique de reconfiguration architecturale multi-niveaux pour la sélection des architectures de déploiement les plus adaptées à un contexte et aux situations associées. Ce cadre a été appliqué au cas de la communication et de la coopération de groupe. Elle a aussi permis de modéliser le style architectural Producteur/Consommateur pour une communication orientée événement. Des règles d'adaptation ont été définies. Elles comportent une partie basée sur SWRL pour la description du contexte et des règles d'adaptation, et une partie basée sur les grammaires de graphes pour la transformation des configurations de déploiement / In this work, we study dynamic reconfiguration of collaborative communicating applications. Providing generic and scalable solutions for automated self-reconfiguration in group collaboration support systems can be driven by rule-based reconfiguration policies. To achieve this goal, we elaborate a dynamic graph-based modeling approach and we develop structural models that can represent the different interaction dependencies from different configuration-related point of views: communication flows between the distributed machines, the networked deployment nodes, and the service composition. Our solution is based on graph grammars rewriting. We provide graph transformation to specify rules for changing deployment architecture while being in conformance to an architectural style. In order to handle the complex design of communicating collaborative system architectures and the related adaptation issues, we propose a multi-layer modelling approach. This approach assures generic solutions for automatic context aware adaptation. Our approach is based on the observation that semantic data analysis that can be exploited to manage priorities and more generally to manage communications. This allows us to represent, in a richer way, the semantics of the managed systems

Nous nous intéressons à l'analyse des exigences de performabilité des systèmes communicants mobiles par model checking. Nous modélisons ces systèmes à l'aide d'un formalisme de haut niveau issu du π-calcul, permettant de considérer des comportements stochastiques, temporels, déterministes, ou indéterministes. Cependant, dans le π-calcul, la primitive de communication de base des systèmes est la communication en point-à-point synchrone. Or, les systèmes mobiles, qui utilisent des réseaux sans fil, communiquent essentiellement par diffusion locale. C'est pourquoi, dans un premier temps, nous définissons la communication par diffusion dans le π-calcul, afin de mieux modéliser les systèmes que nous étudions. Nous proposons d'utiliser des versions probabilistes et stochastiques de l'algèbre que nous avons défini, pour permettre des études de performance. Nous en définissons une version temporelle permettant de considérer le temps dans les modèles. Mais l'absence d'outils d'analyse des propriétés sur des modèles spécifiés en une algèbre issue du π-calcul est un obstacle majeur à notre travail. La définition de règles de traduction en langage PRISM, nous permet de traduire nos modèles, en modèles de bas niveau supports du model checking, à savoir des chaînes de Markov à temps discret, à temps continu, des automates temporisés, ou des automates temporisés probabilistes. Nous avons choisi l'outil PRISM car, à notre connaissance, dans sa dernière version, il est le seul outil à supporter les formalismes de bas niveau que nous venons de citer, et ainsi il permet de réaliser des études de performabilité complètes. Cette façon de procéder nous permet de pallier à l'absence d'outils d'analyse pour nos modèles. Par la suite, nous appliquons ces concepts théoriques aux réseaux de capteurs sans fil mobiles. / We are interested in analyzing the performability requirements of mobile communication systems by using model checking techniques. We model these systems using a high-level formalism derived from the π-calculus, for considering stochastic, timed, deterministic or indeterministic behaviors. However, in the π-calculus, the basic communication primitive of systems is the synchronous point-to-point communication. However, mobile systems that use wireless networks, mostly communicate by local broadcast. Therefore, we first define the broadcast communication into the π-calculus, to better model the systems we study. We propose to use probabilistic and stochastic versions of the algebra we have defined to allow performance studies. We define a temporal version to consider time in the models. But the lack of tools for analyzing properties of models specified with π-calculus is a major obstacle to our work and its objectives. The definition of translation rules into the PRISM language allows us to translate our models in low-level models which can support model checking, namely discrete time, or continuous time Markov chains, timed automata, or probabilistic timed automata. We chose the PRISM model checker because, in our best knowledge, in its latest version, it is the only tool that supports the low-level formalisms that we have previously cited, and thus, makes it possible to realize complete performability studies. This approach allows us to overcome the lack of model checkers for our models. Subsequently, we apply these theoretical concepts to analyse performability of mobile wireless sensor networks.

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