Pattern-based model refactoring for the introduction association relationship

Refactoring is an important software development process involving the restructuring of a model to improve its internal qualities without changing its external behavior. in this paper, we propose a new approach of model refactoring based on the combined use of uml, b and csp. uml models are described by class diagrams, ocl constraints, and state machine diagrams. we detail a refactoring pattern that allows for the introduction of an association relationship between two existing classes. we illustrate our proposal by giving a case study involving the saat (software architecture analysis tool) system