Proceedings

3. ONTOLOGIES
3.1. Briefly about ontology
For many years, the ontology science has been used in Knowledge Engineering (IC)
and Artificial Intelligence (IA) in order to structure the concepts of the specific field
of study. The ontology allows the definition of overall concepts shared within a field
of study, in a formal, explicit, referential and consensual manner (Gruber 1993; Studer
1998). This presents the organization of the concepts and relationships. The
ontology’s core contains four (Stumme & Maedache, 2001):
where:
O:=(C,≤C, R, ≤R)
C represents the set of concepts,
≤C represents the partial order on C,
R represents the set of relationships defined on CxC, and
≤R represents a partial order on R.
Once defined, an ontology must be clear, coherent, intelligible and easy to use and
expand (in fact, easy to update when an evolution occurs).
3.2. Ontology for e-learning
E-learning training technology is based on the following elements: the actors
(students, tutors, designers, administrators); learning fields; educational resources
used for learning (courses, cases of study, complementary documents). The basic
elements are modulated as sub-technologies of the global training ontology.
Nowadays, many researches are based on ontologies for indexing and accessing of
pedagogical objects in support systems for e-learning training (Abel et al., 2003;
Lenne et al., 2005; Knight, 2005). Semantic representation of pedagogical objects is
based on two important concepts: field ontology and training ontology, respectively.
Elements of the field ontology
The field ontology describes the specific concepts of a certain application field, such
as, Data Analysis, Financial Management, Databases, and so on. This is an explicit
and formal specification of a shared conceptualization, proper to a particular
application field (Borst, 1997; Charlet et al., 2008). In addition, it presents the
advantage of allowing a normalization of the concepts, which provides a better
representation of knowledge. The concepts represent the objects, precepts and ideas of
the field and the relationships represent the connections between these concepts.
Actually, the structure of the field ontology defines the relationships established
between the concepts.
The reference literature on the field ontology conveys the following terms: concept,
relationship and axiom. Within an ontology, a concept is uniquely identified and its
various meanings are represented by labels. Semantic relationships represent a type of
interaction between the concepts of the application field. The concept’s links can be
taxonomic (relation of specificity/generality) or non-taxonomic (also-called
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