Formal specifications of user requirements

There is a wide gap between informal requirements and a formal object-oriented specification. To help bridge this gap, we propose that a formal and executable user-centred model should be constructed initially. The user-centred model, which specifies the behaviour that the environment expects from the system, is expressed in terms of agent views and gives very early feedback to the requirements' capture process. Once the user-centred model has been validated with respect to the environment, it can be used as a step in the construction and validation of the formal object-oriented specification.