Ontology-Based Database Approach for Handling Preferences - Data Warehousing Design and Advanced Engineering Applications - page 260

Table 6. Definition and instantiation of PREFERENCE_URI

PREFERENCE_URI Definition
ENTITY PREFERENCE_URI
code: INTEGER;
name: STRING;
classification: STRING;
END ENTITY;

Figure 4. Graphical representation of ontology resource definition

Ontology Model Resource Definition:
Property_ or_Class_Instance

Interpreted Preferences

Interpreted preferences are those preferences
that can be given an interpretation through of an
evaluation. The nature of their definition depends
on the attached interpretation function. They can
be associated to an evaluation or interpretation
procedure. For example, we can interpret the
preference cheap(x) as being price(x) < =20 . The
idea is to define preferences associated to data
types that are valuable and for which there exists
an order relation.
Enumerated preferences are interpreted by a
set of property values or class instances imported
from the ontology instances (Table 7). It corre-
sponds to the enumeration of individuals taken in
an ontology that interprets a given preference. For
example, we could define 'cheap' hotels as be-
ing { Hotel(Formule1 ), Hotel(PremiereClasse) }.
This set, expresses that the 'cheap' preference
corresponds to two hotels in the ontology and
corresponds to #40 in Table 7.
Numeric preferences are interpreted by nu-
meric values. For example, the rating of a hotel
can be defined according to the numbers of stars
the hotel is associated to (e.g., 1, 2, 3, or 4 stars ).

Our approach consists in associating any prefer-
ence model to any ontology resource model that
allows to manipulating the model of the ontology
through its meta-model. Indeed, according to
Figure 4, the preference resource concept of the
preference model is associated to the Property_
Or_Class_Instance entity of the ontology model.
The ontology's instances are taken into account
in the preference model by referring to their cor-
responding ontology's entities. Preferences can be
expressed on property or class instances.
The PROPERTY_OR_CLASS_INSTANCE
resource is defined in EXPRESS according to
the expression in Table 5. It represents a property
instance or a class instance. Indeed, as it is shown
in Figure 2, this resource is a select type (union
of types) between the CLASS_VALUE type and
PROPERTY_VALUE type available in any exist-
ing ontology model.
The preference model introduces specific
resources allowing to defining preferences. Two
categories of preferences are introduced: inter-
preted and uninterpreted preferences.