Model projection: simplifying models in response to restricting the environment

This paper introduces Model Projection. Finite state models such as Extended Finite State Machines are being used in an ever increasing number of software engineering activities. Model projection facilitates model development by specializing models for a specific operating environment. A projection is useful in many design-level applications including specification reuse and property verification. The applicability of model projection rests upon three critical concerns: correctness, effectiveness, and efficiency, all of which are addressed in this paper. We introduce four related algorithms for model projection and prove each correct. We also present an empirical study of effectiveness and efficiency using ten models, including widely studied benchmarks as well as industrial models. Results show that a typical projection includes about half of the states and a third of the transitions from the original model.