Details of Grant 

EPSRC Reference:	GR/J15483/01
Title:	INCONSISTENCY HANDLING IN MULTI-PERSPECTIVE SPECIFICATIONS
Principal Investigator:	Kramer, Professor J
Other Investigators:	Nuseibeh, Professor B Gabbay, Professor D Finkelstein, Professor A
Researcher Co-Investigators:
Project Partners:
Department:	Computing
Organisation:	Imperial College London
Scheme:	Standard Research (Pre-FEC)
Starts:	28 July 1994	Ends:	27 January 1998	Value (£):	185,777
EPSRC Research Topic Classifications:	Artificial Intelligence
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:
Summary on Grant Application Form
This project, VOILA, combines two novel and promising lines of research in software engineering: the ViewPoints approach to distributed development of systems and inconsistency handling in logic. The objectives are twofold:(1) to facilitate distributed development of multi-authored, multi-perspective software specifications, described in multiple viewpoints; and (2) to provide sound techniques for handling inconsistencies that occur naturally in such specifications, not by eradicating them immediately, but by using any useful information they contain as a trigger for taking further appropriate actions. Progress:The development of most large and complex systems necessarily involves many people - each with their own perspectives on the system defined by their knowledge, responsibilities, and commitments. To address this we advocate distributed development of such specifications with support for each of the multiple autonomous perspectives. Inevitably, the different perspectives of those involved in the process intersect - giving rise to a need for coordination. The problem of coordinating these different perspectives is partly organisational and partly technical. The organisational aspect requires that support is provided for ordering activities and for interacting by passing information, usually in the form of specifications. The ViewPoints framework for multiuser distributed software development provides this support. The main technical aspect centres around the consistency relationship between these perspectives, given as partial specifications. Local consistency can be readily maintained within each perspective. However, there is a need for identifying and handling inconsistencies between perspectives (ViewPoints). Maintaining absolute consistency between perspectives at all times is not possible. Often, it is not even desirable since this can unnecessarily constrain the development process and may lead to a loss of information. Indeed since the real world forces us to work with inconsistencies, we believe that we should make more provision for living with inconsistency. Inconsistency is an inevitable part of the software development process. In order to develop a practical and logical means for inconsistency handling, we are exploiting the integration and organisational capability of the ViewPoints framework. We rewrite information in a Viewpoint as a set of logical formulae, and view the inconsistency handling as being equivalent to inconsistency handling in distributed logical databases. For formalisation of inconsistency handling we use an action-based meta-language based on linear-time temporal logic, where we allow quantification over formulae. Using temporal logic, we can specify how the databases of hypotheses (the ViewPoints) and data (local specifications) should evolve over time. In this way, we can view the meta-level handling of inconsistent ViewPoint specifications in terms of satisfying temporal logic specifications. In addition, the meta-language is used to describe the required actions to be undertaken when discovering an inconsistency, where the choice of actions is dependent on the larger context. Some of these actions may make explicit internal database actions such as invoking a truth maintenance system, while others may require external actions such as seek further information from the user. We are also investigating the use of a non-trivializable quasi-classical logic for reasoning in the presence of inconsistency and evaluating an approach to decentralised process modelling which is based on the recognition of particular situations in the states and histories of individual ViewPoints.
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Organisation Website:	http://www.imperial.ac.uk