Structure and semantics in OODB class specifications
James Geller, Yehoshua Perl, Erich J. Neuhold · ACM SIGMOD Record · 1991
A class specification contains both structural aspects and semantic aspects. We introduce a mathematically based distinction between structural and semantic aspects. We show how this distinction is used to identify all structural aspects of a class specification to be included in the object type of a class. The model obtained is called the Dual Model due to the separation of structure and semantics in the class specification. Advantages of the separation of structure and semantics have been discussed in previous papers and include separate hierarchies for structural and semantic aspects, refined inheritance mechanisms, support of physical database design and structural integration which is impossible in other models.