[topicmapmail] Emancipating Instances from the Tyranny of Class

[Sam Hunting]

A paper with a title that is the same as the subject line of this mail
can be found at:

    http://citeseer.nj.nec.com/parsons00emancipating.html

I think it has particular relevance to large information owners, since
their instances are most at risk from "the assumption of inherent
classfication" (see below). At the same time, developers who need to
take the interests of large information owners into account may find it
of interest.

Here is an extract from the abstract:

    Database design commonly assumes, explicitly or implicitly, that 
    instances must belong to classes. This can be termed THE ASSUMPTION

    OF INHERENT CLASSIFICATION. We argue that the extent and
    complexity of problems in schema integration, schema evolution, and
    interoperability are, to a large extent, consequences of inherent  
    classification. Furthermore, we make the case that the assumption
of    
    inherent classification violates philosophical and cognitive 
    guidelines on classification and is, therefore, inappropriate in 
    view of the role of data modeling in representing knowledge about 
    application domains.

Here is an interesting paragraph:

    classes serve to provide useful abstractions of similarity to one
    or more persons [Lakoff 1987]. In other words, things exist, but 
    classes are constructed. Moreover, since what is useful varies over

    time and among individuals, there is no single “correct” way to 
    classify a given set of instances – multiple classification 
    structures are possible [Parsons and Wand 1997a].

Here is an extract from the conclusion:

     Both the hierarchical and network data models included mechanisms 
     to link records (or segments). These links locked into the data 
     model information about the application domain. This supported 
     efficient operations for specific applications. However, at the 
     same time these models imposed constraints 
    on what can be done with the data, and 
     prevented efficient processing if a different perspective had to
be
     accommodated. The relational model freed the records in the 
     database from the tyranny of the links. Instead, it allowed for 
     creating links as needed (via the join operation). This
     flexibility did not come without cost, as it required additional
     processing power and special implementation mechanisms to avoid 
     performance deterioration. In a similar way, we believe that tying
     instances to classes, while reflecting a given view of the
     application domain, imposes constraints on the ability to use 
     alternative and varying views.

Hope this is at least inspirational! (The paper also includes an
architecture and some (not overpowering) math.)

S.

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