Software concurrent systems such as electronic financial services are very popular today. Rigorous testing of such systems is indispensable. Nevertheless, the state-explosion problem, in which the size of a system grows exponentially with the number of concurrent components, is a severe obstacle to the generation of test cases.In this study, we propose a new relationship assuring the conformities of test cases for concurrent systems. We stipulate it in Communicating Sequential Processes (CSP), which is an excellent tool to study concurrent systems. Specification of concurrent systems is expressed as processes that are composed sequentially and concurrently. Our proposal supports both abstraction and process composition.This approach decomposes a given process into sequential compositions of component processes. Each component can be anti-extended into abstract forms. Sequential and concurrent combinations of abstract forms can substitute their corresponding extending components in a process to form aggregated abstract forms. Since the given processes, components and abstract forms are all processes, this approach can be applied recursively and compositionally. We prove that these aggregated abstract processes should be anti-extensions of the corresponding processes under a few necessary and sufficient conditions. Hence, test cases generated from these processes will be conformance test cases for the implementations.We examine three major testing relations (conformance, extension and reduction) from the point of view of their ability to support abstraction. Extension and reduction are special kinds of conformance, which are partially ordered. However, only extension from a specification can provide abstract forms that guarantee to be conformed by an implementation of the specification. Extension is further investigated to support the compositional approach. We identify five weaknesses of extension, which we call problems of preceding, succeeding, prefix, decomposition and paralleling. Each will result in non-conforming abstraction.To resolve the identified weaknesses of extension in a compositional and abstractionoriented approach, we formulate σ-extension and identify the necessary and sufficient conditions. We also discuss a restricted sub-class of process specification so that these conditions can easily be satisfied. In the restricted sub-class, successful terminations of processes are deterministic.Under these conditions, we achieve a few desirable properties. First, both preceding and succeeding components of a given sequential composition can be anti-extended. The given composition should extend the sequential composition of its corresponding anti-extended processes. Secondly, a given parallel composition whose concurrent components are sequential compositions should extend a parallel composition of anti-extensions of preceding components of corresponding sequential compositions, followed by a parallel composition of anti-extensions of corresponding succeeding components. Furthermore, a given sequential co...

of thesis entitled "Inheritance and OMT: a CSP approach" submitted by Mr Chan Wing Kwong for the degree of Master of Philosophy at The University of Hong Kong in September 1995 Much research has been conducted on the formulation of inheritance in object-orientedness. Most proposals retain the semantic relationship between the superclass and subclass, but deliberately ignore the issues of overriding, which plays an important role in object-oriented modelling. Others use class inheritance and module inheritance to distinguish between the cases of inheritance with and without overriding, but, as a result, one fundamental concept is partitioned into two. Some research supports overriding, but not transitivity. This thesis addresses the issue of overriding in object-orientedness, illustrates how a single inheritance concept can be formalized using Communicating Sequential Processes (CSP), proposes a refined concept of conformance which is transitive, and demonstrates the practical application of our theory. This project compares favourably with other related work. In this thesis, we identify that reflexivity, anti-symmetry, transitivity, overriding, behavioural compatibility, formality, incrementality and multiple inheritance are the desirable features of a theory of inheritance. We formalize the concept of behavioural inheritance as a special kind of conformance relation that links a subclass to its superclass by the Fidge's priority choice operator. Using the priority choice operator, we integrate naturally the concept of overriding into our formalization and provide a support for an incremental development. Transitivity is realized by the introduction of strong conformance which can be used as a unification of extension and reduction. It also provides a framework of reflexivity and anti-symmetry for the inheritance relation. Through strong conformance, behaviour compatibilities between the superclasses and subclasses can be ensured. We also refine our theory to support multiple inheritance and propose a method to resolve ambiguity raised by multiple inheritance. Finally, a criteria for generating an optimal incremental change will be presented. i ACKNOWLEDGMENTS It is a great pleasure to acknowledge the profound and unusual work of my supervisor Dr T.H.Tse, M.B.E., the exciting insights in his pioneer work on methods integration, and his professional enthusiasm in the persuade of knowledge. Without his influence, his support, and his kind and interesting discussions and personal friendship, I can hardly imagine the sunshine and the fresh air flourished in this project. Sincere thanks should equally and dedicatedly be given to Dr T.Y. Chen, Dr F.C.M. Lau and Dr David W. Cheung for their kind but formal and justifiable appraisal of the research. I am glad to have a chance to enjoy the warmth and care of the The Software Engineering Group,