Enhancing soft systems analysis with formal modelling

Broadly, the paper argues for a soft systems approach to initial requirements definition and for the use of formal techniques as a means of strengthening that approach. In detail, the paper looks specifically at the means and implications of combining Checkland and Wilson's Soft Systems Methodology (SSM) with formal specification in LOTOS (P.B. Checkland, 1981; B. Wilson, 1990). Formal descriptions give precise meaning to the largely informal SSM models and help establish a bridge to traditional computing oriented analysis techniques. The use of tools to support the development, linking and maintenance of SSM and LOTOS models is also examined. The discussion is illustrated with a simple book ordering data processing example. Overall, this work is part of a larger research effort into the development of RACE, a new requirements engineering method for software.