7.1.4 The ontology


Although the text is fairly short it contains a variety of words, each of which requires some consideration. Among the interesting problems in this text are:

The ambiguous word "before"

"Before" can be a temporal relation (I will finish eating before you do), but in this text it is a spatial relation. Prolog+CG does not require an explicit hierarchy of relation types, but it should be noted that the semantics of the domain is represented using an implicit hierarchy of such relations. The same goes for "until" and "from".

The use of pronouns

In this representation we have chosen to represent the text in a fairly verbatim manner, including the use of personal pronouns. In order to do this, a category [pronoun] has been added as a subtype of the category [person].

The result

The result may look like this:

// Type hierarchy
universal > object, process, proposition.
object > person, artifact.
person > pronoun.
artifact > weapon.
weapon > dagger.
process > act, state.

// Catalogue of individuals
act = ask, say.
person = Macbeth.
pronoun = pr_I, pr_me.

The basic premise

The basic premise behind this kind of formalization is that a lot of the semantic information in a conceptual graph can be found in the type-hierarchy.

The premise is that the type-hierarchy explicates distinction which are relevant to the purposes and intentions of the formalizing agent (you, for example), and that the type-hierarchy says significant things about the formalized domain, and how it is conceptualized or categorized.

Big questions lurk just beneath the surface here! You may find it useful to consider some of the philosophical issues at work, e.g. the debate between the realists and the conceptualists about universals vs. concepts.

This premise presupposes that care has been taken in constructing the type-hierarchy.

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