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From: jensen@skinfaxe.diku.dk (J|rgen Jensen)
Newsgroups: comp.object
Subject: Re: ??Bidirectional Inheritence??
Message-ID: <1990Oct20.220803.25176@diku.dk>
Date: 20 Oct 90 22:08:03 GMT
References: <6957@uwm.edu>
Sender: news@diku.dk (The Netnews System)
Organization: Department Of Computer Science, University Of Copenhagen
Lines: 38


In some other connection I stumbled across something like this
yesterday.  In the book "Readings in Artificial Intelligence
and Databases", edited by John Mylopolous and Michael Brodie
(ISBN 0-934613-53-2) there is a section 2.2.3 entitled "On the
design and Specification of Database Transactions, written by 
Michael L. Brodie and Dzenan Ridjanovic.

Quotes:

    [p. 187]
    3. Structure Modelling
    3.1 Extended Semantic Hierarchy Model (SHM+)

       For the design and specification of structural properties of 
    database applications, SHM+ provides one structural concept, the
    object, and four forms of data abstraction for relating objects:
    Classification, aggregation, generalization, and association.
    [...]
    _Classification_ represents an _instance-of_ relationship between
    and object class in a schema and an object in a database.  [...]


    [p. 188]
    Aggregation and association support upward inheritance in which
    properties of the componenents for members are inherited by the
    aggregate or set.  For example, the properties of the components
    _employee-name_, _employee-number_, and _salary_ are inherited
    as properties of the aggregate _employee_.  Aggregates and sets
    are designed by _decomposition_ into, or _composition_ from
    components or members without concern for their properties.
    Generalisation supports downwards inheritance in which all
    properties of a generic object are inherited by each of its
    category objects.

end quotes.
 . . . . . . . . . . . . . . . . . . . . . . . . . . j e n s e n
(jensen@diku.dk)