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A model is, fundamentally, an abstraction - the removing of extraneous information from an assertion of "reality" in order to create an analog to a given entity or process that is more tractable to understanding or representation. You are giving up fidelity for simplicity with any model, and the more you simplify, the more tractable the model becomes, but at the cost of loss of fidelity when the model is scaled to the broader domain. In physics, for instance, you teach beginning physics students the world of perfect motion - frictionless surfaces, infinitesimally short impulses, perfectly elastic collisions - because these things are easier to understand, yet after a relatively short period of time most students realize that the world that they are modeling does not in fact have much real correlation with their observed reality. Then you slowly introduce friction (first as a linear differential equation then later as a very non-linear one), you introduce inelastic collisions, relativistic and quantum effects. You are adding more "terms" here, but at the cost of greater complexity, non-linearity, fractals and even emergent behaviors, and often at the cost of going from certainty to great uncertainty about the role of specific characteristics in the model
The same holds true in the ontological space. Ontologies are models that represent a consensus of perceived need, but these models are by their very nature incomplete, because the perceived needs of a model may vary considerably from one individual to the next (especially once constraints and interactions with other models is also taken into account). The best models are those that describe the Venn intersection of common interests vary well, that describe the less intersected domains of interest moderately well via abstraction, and provides an effective mechanism for both delineation of non-interests and a mechanism for extending peripheral interests, albeit with far less fidelity. Verbosity really doesn't enter into it - the description of an aircraft avionics systems may have tens of thousands of precise terms, but still may be inadequate to describe the domain, while other schemas may have a dozen or less terms but be generally quite descriptive, perhaps overly so. The question is whether the domain being modeled is expressing those parts it needs modeled most more accurately than it is those that represent interstitial connections and external processes or objects, and whether this description is adequate to the task at hand.
Kurt Cagle Managing Editor, XMLToday.org 443-837-8725 On Sun, Dec 18, 2011 at 4:06 PM, Len Bullard <cbullard@h...> wrote: Not sure about the case for schema or instances of it, but with DTDs as the
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