Use Case Maps as an Aid in the Construction of a Formal Specification

Abstract

A Use Case Map (UCM) is a scenario-based visual notation facilitating the requirements definition of complex systems. A UCM may be generated either from a set of informal requirements, or from use cases normally expressed in natural language. Natural languages are, however, inherently ambiguous and as a semi-formal notation, UCMs have the potential to bring more clarity into the functional description of a system. It may furthermore eliminate possible errors in the user requirements. The semi-formal notation of UCMs aims to show how things work generally, but is not suitable to reason formally about system behaviour. It is plausible, therefore, that the use of UCMs as an intermediate step may facilitate the construction of a formal specification. To this end this paper proposes a mechanism whereby a UCM may be translated into Object-Z.