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  1. OMG Issue

UML14 — Generalization should be meta-metamodel element

  • Key: UML14-959
  • Legacy Issue Number: 2850
  • Status: closed  
  • Source: Anonymous
  • Summary:

    Summary: UML 1.3 Metamodel Semantics

    Generalization should be meta-metamodel element

    It is a generally accepted fact that generalization is a second order
    relation, ie, a relation whose elements (instances) are pairs of
    types (classifiers, or whatever). Associations, by contrast, are
    first order: their elements are tuples of objects (individuals,

    UML is based on a four-layer metamodel structure, including metamodel
    and meta-metamodel layers. Why, then, do Generalization and
    Association appear on the same layer, namely the metamodel? Much more
    troublesome: How can they be specializations of the same
    generalization, namely Relationship? Together with the defined
    implication of generalization: "The more specific element is fully
    consistent with the more general element (it has all of its
    properties, members, and relationships) ..." [UML 1.3, sect. 2.5.2]
    this leads to a paradox, because generalization itself would be
    inherited. The paradox would be avoided, however, if generalization
    were a relation of the meta-metalayer.

  • Reported: UML 1.2 — Fri, 13 Aug 1999 04:00 GMT
  • Disposition: Resolved — UML 1.3
  • Disposition Summary:


  • Updated: Fri, 6 Mar 2015 21:37 GMT