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IADIS International Conference WWW/Internet 2010The outcome of this operation is a discourse defined, in the linguistic field, as a “... formal discussion of asubject in speech or writing 2 ”. In a broader sense, this definition can be extended as a “...system ofrepresentation consisting of a set of representational codes for constructing and maintaining particularforms of reality within the ontological domain defined as relevant to its concerns” (Clandler, 2001).These semiotic categories can be used to analyze other kinds of 'discourses', such as movies orhypermedia. In movies domain, we have syntagmatic elements such as long shots, close up, travelings 3 thatare matched with sound (special effects, music and dialogues), that are arranged to transmit the film maker orauthor's intention according to some paradigmatic composition 4 . Lets us move to LO field in order to discusssome of its semiotic aspects.4. LEARNING OBJECTS AS SIGNSWhen a user interacts with a learning environment (LE) he/she establishes a communication link since theusers (receptor/leaner) and a sender (LE) interchange messages. There is, surely, another ‘virtual’ element,the author, represented by the LE. Messages are structured as a discourse composed by syntagmas andstructured according to some system, or paradigm. This is not a linear discourse since it comprises differentmedias and different and simultaneous codes.A Knowledge Domain (KD) can be represented by means of ontologies which are the formalrepresentation of the concepts and relationships on a domain (conceptualization) (Gruber, 1993). Ontologiescan are represented as assertions expressed by means Description Logic axioms. These assertions can berepresented in a machine understanding form by means of OWL DL, a subset of the family of XML-basedlanguages proposed by W3C consortium (Antoniou, 2008).The abstract form of ontology is provided by Description Logics, whose main constructs are the set ofaxioms, terminology elements and facts. Let us consider, for instance, a set of concepts C and a binaryrelationship dependsOn, represented by D. The dependence relationship between the concepts C 1 and C 2 ,conceived as classes of individuals, is expressed in Description Logic as , the set of instances (orindividuals) of C 1 that depends on the instances of C 2 . The relationship between concepts can be representedas a graph, where nodes represent the concepts and edges, the relationship between them. Then, it is possibleto retrieve paths from a concept to another, which is equivalent to exploring the semantic relationships oflearning content to guide the LOs’ composition.We can apply these concepts to model a small knowledge domain with only one type of relation. In orderto do this we built an ontology for the Introductory Physics sub domain in order to do a preliminary test forthe proposed method.5. AN EXAMPLE FROM INTRODUCTORY MECHANICSFrom the considered sub domain, we choose a set composed by the concepts: Mass, Force, Work, Velocity,Derivative, Squared Velocity (SquaredVelocity), Acceleration, Conservative Force (ConsForce), Limit,Potential Energy, Kinetic Energy and Energy. An Ontology for this set was constructed as OWL DL classesusing Protégé 4.1 5 editor, a free open source editor and knowledge base framework and its graphicalrepresentation using the OntoGraph plug-in is displayed in Figure 3, where the dotted arrows mean therelation DependsOn and continuous ones stand for the inferred relationship hasSubClass. In order toaccomplish the requirements of the proposed approach we have also defined some relationships between LOsand concepts using the LOM structures mapping them to the ontology.2 Random House, Webster's Everyday Dictionary.3 Travelling refers to the camera movement following the actor walking keeping the same relative position (Source: www.wipedia.org).4 According to (Metz, 1972) paradigmatic features in a semiology of movies is somewhat feeble, since the inventory of probable units isopen, although finite.5 http://protege.stanford.edu/31