Research On Relation Between Pi-Calculus And Dynamic Description Logic DDL And Its Application

Pi-Calculus proposed by Robin Milner, is a kind of concurrent theorywith the research emphasis on mobile communication between processes, isable to create new links, and has been called as a calculus of"mobile"processes used to model concurrent and dynamic systems. SoftwareArchitecture (SA) is a significant aspect of the design of any software system,which defines the structure of components, their interrelationships, thecomposing pattern and satisfied constraints, and the principles and guidelinesgoverning their design. Pi-Calculus can be used for modeling dynamicsystems, is the mathematic basis for Architecture Description LanguagePi-ADL, and provides an appropriate description of distribute and concurrentarchitecture.Description Logic (DL) is a decidable fragment of First-Order Logic(FOL), providing better expressing ability and decidable reasoning. Ontologyis an explicit, formal specification of a sharing, conceptual model to a domainof interest, which is seen as the foundation and key to realize the semanticlevel sharing of Semantic Web. As an efficient tool for the classificationrepresentation of knowledge according to the inheriting relation, DL hasbecome the logic foundation for ontology modeling. Currently, in a moreopen and dynamic environment of Semantic Web, due to the changes in theapplication's domain or the user's requirements, the domain knowledgechanges over time and ontology evolves continually. Ontology evolution isthe timely adaptation of an ontology to the arisen changes and the consistentpropagation of these changes to dependent artifacts to maintain theconsistency of the ontologies in Semantic Web. Dynamic Description Logic(DDL) is the extension of traditional DL, which can effectively support therepresentation and reasoning of both static and dynamic knowledge andprovides an appropriate logical foundation to SemanticWeb.Pi-Calculus supports the modeling of dynamic systems, and DDL candenote and infer both static and dynamic knowledge, thus they will be morewidely used in practice if the relations between them are established. So thispaper analyzes the relations between Pi-Calculus and DDL, and proposes thetwo instances which are A DDL–Based Software Architecture Model and A Pi-Calculus Based Ontology Evolution Method.Firstly, analyze the relation from Pi-Calculus to DDL. Firstly, from bothstatic and dynamic structure, a number of Pi-Calculus process definitions aredescribed using DDL so as to illuminate the logical structures of processesand the logical relation changes between processes: from static structure, theprocesses and communicating ports of Pi-Calculus are denoted as the DDLconcepts, and their interrelations are described as the DDL relations; actionsare used to assist the concepts to describe the correspondence from severalprocess definitions to DDL which illuminates the dynamic structure ofprocess. Secondly, the correspondence relation between the reasoningmechanism of DDL and the consistency detecting of Pi-Calculus baseddynamic system is explained. This work indicates that the decidablereasoning of DDL can solve the consistency detecting problems ofPi-Calculus based dynamic system.Secondly, analyze the relation from DDL to Pi-Calculus. Firstly, define akind of process model based on Pi-Calculus: entities of DDL, includingconcepts, relations and individuals, are presented as Pi-Calculus processes;some communication links between processes exist for all related entities,including between concepts and relations, concepts and individuals, andrelations and individuals; one entity can transfer messages to another oneassociated with it by the link between them to show the changes of therelations between entities. Secondly, analyze the semantics of ALCdescription logic, TBox and ABox: the semantic based on process modelinterprets concept as a subset of the whole set of certain communicating portsand relation as a binary relation on the whole set; in TBox, concept definitionis used for creating new process, and concept subsumption is used forexplaining the semantic restriction of process; in ABox, concept assertionmeans to establish a new link between the processes of concept andindividual, and relation assertion means to establish two new links betweenthe processes of relation and individuals. Finally, taking the bicycle-sellingphenomenon as an example, describe the change processes of DDL-baseddynamic knowledge using the communicating process on the communicatinglinks of Pi-Calculus. This work indicates that the descriptive ability todynamic system of Pi-Calculus can solve the description problems of thechange processes of the DDL-based dynamic knowledge. Thirdly, based on the relation analysis from Pi-Calculus to DDL,propose a kind of DDL–based software architecture model. Firstly, fromcomponent, port, type, connector and composite component, describe the SAusing concepts, relations and actions of DDL. Secondly, describe an exampleof a complete architecture model of Pipeline-Filter style from DDLdescription language, TBox, and ABox. Finally, demonstrate thecorresponding relations between the reasoning of DDL and the consistencydetection of SA, and illustrate that the reasoning of DDL can detect someinconsistency problems of dynamic SA by an instance. It is obvious that thissoftware architecture model facilitates the description of each part of SA aswell as the constraints between them, and supports the consistency detectionof the dynamic architecture at the same time.Finally, based on the relation analysis from DDL to Pi-Calculus,proposea kind of Pi-Calculus based ontology evolution method. Firstly, describe akind of Pi-Calculus based ontology process model: entities of a concreteontology including concepts, properties and instances are presented asprocesses, associations between entities are denoted as the links betweenentity processes, and an entity can interoperate with another one associatedwith it by the link between them, providing the foundation to realize theontology evolution process. Secondly, based on the ontology process model,discuss the change implementation and propagation of ontology evolutionprocess at three levels: the change implementation of single ontologyevolution, the push-based synchronization realization for the changepropagation in the evolution of multiple dependent ontologies within a singlenode, and the pull-based synchronization realization for the changepropagation of the distributed ontologies evolution. It is obvious thatPi-Calculus provides a kind of formal basis for the realization of ontologyevolution process.There is a lot of work need to do to perfect this paper, for example, thecorrespondence from process (x)P to DDL is not discussed, and theproblem of variable scopes can be solved using the name substitutionprinciple; for the DDL-based software architecture model, to define thecorresponding ADL (Architecture Description Language), to develop thesupport system, and to do the further research on applying DDL to theconsistency detection of dynamic software architecture; to refine the definitions of the Pi-Calculus based ontology process model and the ontologychange operations, to consider the change validation based on the model, andto develop the tools to support the ontology evolution process; etc.The future work is: based on the fruits of research on Pi-Calculus andDDL, to perfect the relation analyses between them, the DDL–based softwarearchitecture model and the Pi-Calculus based ontology evolution method, tomake them be more widely applied in practice.