Strategies for Consistency Checking, the Choice of Unification

There is increasing interest in models of system development which use multiple viewpoints. Each viewpoint offers a different perspective on the target system and system development involves parallel refinement of the multiple views. Our work particularly focuses on the use of viewpoints in Open Distributed Processing (ODP) which is an ISO/ITU standardisation framework. Multiple viewpoints, though, prompt the issue of consistency between viewpoints. This paper describes an interpretation of consistency which is general enough to meet the requirements of consistency in ODP. Furthermore, the paper investigates strategies for checking this consistency definition. Particular emphasis is placed on mechanisms to obtain global consistency (between an arbitrary number of viewpoints) from a series of binary consistency checks. The consistency checking strategies we develop are illustrated using the formal description technique LOTOS. Keywords: Viewpoints, Consistency, ODP, Formal Description Techniques, LOTOS.