ABSTRACT Unified Modelling Language (UML) is the most popular modelling language use for software design in software development industries in which class diagram is being the most frequently used diagram. Despite the popularity, UML is being affected by inconsistency problems of its diagrams at the same or different abstraction levels. To address inconsistency in UML, this research has specified twenty-four abstraction rules of class’s relation semantic among any three related classes of a refined class diagram to semantically equivalent relations of two of the classes using a logical approach. This research has also formalized three vertical semantic consistency rules of a class diagram refinement identified by previous researchers using a logical approach and the set of formalized abstraction rules. The results were successfully evaluated using hotel management system and passenger list system case studies and were found to be reliable and efficient.
