Improving the UML Metamodel to Rigorously Specify Aggregation and Composition

In object-oriented technology, some concepts are so often used that people have no doubt about their meaning (e.g. class, object, method). This is not the case when abstraction concerns lead to the use of some conceptual representations such as an object being part of another one. Even the standardized notation UML (Uniied Modeling Language { version 1.3) is confusing in some of its deenitions. In this paper 1 , we use the beneets from a formal deenition for the semantics of the Whole-Part relationship to improve the metamodel used in the UML. The aim of the proposed speciication is for it to be incorporated into version 2.0 of UML. Thus it consists of an incremental improvement to the current metamodel, as well as the introduction of axioms.