Sometimes, because of an atypical Situation, ail important mandatory association between classes in a UML Class Diagram Must be replaced by all optional one. That semantic and functional impoverishment happens because the mandatory constraint must have a boolean value. In this paper we analyze the use Of soft constraints in the UML Class Diagram, and their automatic repercussion in the corresponding Relational Model. The soft (deontic) constraints allow the formal representation of requirements, which ideally should always be fulfilled, but can be violated in atypical situations. In this paper we enrich a previous deontic approach, by introducing the ability to explicitly represent the so called Contrary-To-Duties requirements, i.e.. domain integrity requirements that emerge as a consequence of an unfulfilled mandatory constraint. We Support our approach with the UML/OCL language.

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UML,Contrary-to-duties,Relational model,Deontic constraints

• Physical Sciences - Natural Sciences