A deidealisation semantics for KAOS

KAOS is a goal directed requirements engineering framework based on the decomposition and refinement of goals. Decomposition and refinement continue until a point is reached at which agents, identifiable in the application environment, can be assigned responsibility for operations that manipulate variables over which they have control, and where the information for determining changes in the controlled variables resides in variables which the agent can monitor. Although many of the 'refinements' that arise in the KAOS process can be viewed as acceptable according to one or other Model Based Refinement Formalism, many cannot. Those that cannot correspond to 'deidealisation' steps, not covered by conventional refinement formalisms. It is shown that such deidealisations can be seen as retrenchments, and the smooth interworking between refinement and retrenchment leads to a fuller formalisation of the KAOS process than is otherwise possible. © 2010 ACM.