A Concept Language for an Engineering Application with Part-whole 5.5 New Perspectives in O-odm Tennis-club V (= 1 President-mbs Tennis-player) Tennis-player V ( 1 President-mbs Tennis-club) 5.3 Modeling Wholes in Object-oriented Data Models

Knowledge bases, data bases and object-oriented systems (referred to in the paper as Object-Centered systems) all rely on attributes as the main construct used to associate properties to objects; among these, a fundamental role is played by the so-called part-whole relation. The representation of such a structural information usually requires a particular semantics together with specialized inference and update mechanisms, but rarely do current modeling formalisms and methodologies give it a speci c, \ rst-class" dignity. The main thesis of this paper is that the part-whole relation cannot simply be considered as an ordinary attribute: its speci c ontological nature requires to be understood and integrated within data modeling formalisms and methodologies. On the basis of such an ontological perspective, we survey the conceptual modeling issues involving part-whole relations, and the various modeling frameworks provided by knowledge representation and object-oriented formalisms.