The Study On The Theoretic System Of Non-Taxonomic Relations Of Ontology

Ontology is a formal representation of concepts and relations between concepts in the specific domain. Relation is the relevancy between concepts that describe the basic terms or vocabulary in the domain. There are two kinds of relations in the ontology:taxonomic relations and non-taxonomic relations. Taxonomic relations describe the hierarchy of hypernyms and hyponyms while non-taxonomic relations describe the others.Due to the transitivity of the taxonomic relations, concepts make up taxonomy. Using the taxonomy, ontology accomplishes the reasoning about concept satisfiability. Non-taxonomic relations enhance the expressiveness and complexity of ontology in knowledge expression. Ontology with non-taxonomic relations is rising from the taxonomy to the thesaurus, the conceptual model and logical theory. Therefore, the study on the theoretic system of non-taxonomic relations of ontology has important theoretical significance.Non-taxonomic relations are classified into two categories:part-whole relations and attribute-of relations.Part-Whole relations, PW relations for short, are relations between the whole concept and the part concept. If the PW relation is transitive, it structures a partonomy among the whole, the part and the component of the part. Using the partonomy, ontology accomplishes the reasoning similar to the concept satisfiability. In fact, the transitivity of PW relations is ambiguous. In order to reasoning about PW relations in ontology, ontology needs to have a precise, formalized logical system, which can determines the transitivity of PW relations. The intension of the concept includes numerous attributes. Attribute-of relations express that a concept is the attribute of another one. Therefore, we should take the effect of attribute-of relations into account when calculating the similarity between concepts.This thesis discusses the transitivity of the PW relations and the effect of attribute-of relations on the calculating of similarity between concepts.The main work and contributions of the thesis summarize as follows: (1)A new theory that the transitivity of PW relations is determined by semantic constraints is proposed.The ambiguity of the transitivity of PW relations is caused by the semantic diversity. PW sub-relation is a kind of PW relation with specific semantics, which adds the semantic constraints on PW relation. The semantic constraints are determinant factors of the transitivity of PW relations.We found that functional constraint, material constraint and dependent constraint affect the transitivity of PW relations indirectly. Nevertheless, the association of the domain and the range of PW relations (defined as domain & range constraint) affect the transitivity of PW relations directly:the PW sub-relations that do not satisfy domain & range constraint will not satisfy the transitivity. Based on the analysis of the domain & range constraint, we subdivide PW relations and propose taxonomy of PW relations.Using the taxonomy of PW relations, ontology detects the role satisfiability and domain compatibility of PW relations(2) A new theory about the transitivity of the PW relation composition is proposed.The semantic constraints affect the transitivity of the PW relation composition. We judge the possibilities of the transitivity of the PW relation composition through domain & range constraint. According to the functional constraint, material constraint and dependent constraint, the transitivity of the PW relation composition can be determined and the semantic conclusion of the transitivity can be draw. In short, there are several conclusion of PW relation composition:satisfy transitivity, do not satisfy transitivity, satisfy transitivity with some Limitations and do not have the semantic meaning. These conclusions can be use as the axioms of ontology, which is the foundation of logical reasoning.(3) A new approach about the calculation of the similarity between concepts in ontology, intension similarity between concepts (ISBC), is proposed.The similarity between concepts in the ontology is a quantitative measure. In order to distinguish the similarity and the relevance between concepts, the ontology is divided into different views. The similarity between concepts only in the same view has practical significance. There are taxonomic relations and non-taxonomic relations between concepts. The taxonomic relations, which provide the specialization and generalization of concepts, are the main basis of similarity calculation. Concept specialization using the PW relations can modify the taxonomy. Attribute-of relations provide the intension of the concept and play an auxiliary role in similarity calculation. ISBC method considers the effect of attribute-of relations. Due to the concept that described the attribute located in taxonomy, the incompatible attribute will reduce the similarity between the concepts and the compatible attribute will increase the similarity between the concepts. ISBC method considers both structure information of the concept (taxonomic relations) and intension information of the concepts (non-taxonomic relations) adequately. The experiment results show that the ISBC method can describe the semantic distance between concepts accurately.