A Modular Ontology Framework Based on Semantic Interfaces

There are various challenges in developing complex monolithic ontologies such as reduced reasoning performance, increased complexity in maintenance, and difficulty in integration. The development of ontologies in a modular manner can address these issues and enhance understandability, reusability and evolvability of ontologies as well as lead to better performance on ontology reasoning.;This thesis proposes the Semantic Interface-based Modular Ontology Framework (SIMOF), a framework for developing and maintaining ontology modules and modular ontologies based on the notion of semantic interfaces. Semantic interfaces abstract the semantics of ontology modules from different points of views and enable the smooth integration of independently-developed ontology modules. SIMOF is composed of three main components: Interface-Based modular ontology Formalism (IBF), revision management component, and quality management component. IBF, as the core component of SIMOF, provides formal definitions for the syntax and semantics of ontology modules, interfaces, and modular ontologies based on the formal semantics of description logic knowledge bases. IBF also supports reasoning and query processing over modular ontologies based on a proposed module augmentation procedure as well as existing algorithms for reasoning over description logic knowledge bases.;The revision management component supports revising ontology modules. A revision operator is proposed that satisfies some of the most important postulates of the belief revision theory. In addition, a revision algorithm is proposed that resolves inconsistencies induced by module modifications. The quality management component analyzes the quality of ontology modules. A set of quality metrics are proposed for measuring the quality of ontology modules and modular ontologies. These metrics are based on semantic-based definitions for dependencies between local and external knowledge represented in ontology modules.;The prototype implementation of SIMOF includes an extension of the Web Ontology Language (OWL) that is designed based on IBF, an extension to the SWOOP ontology editor for developing modular ontologies, a new reasoner for modular ontology reasoning, and a query engine for executing conjunctive queries over modular ontologies. Two application examples of SIMOF are also described in this thesis for applying modular ontologies in real-world domains of discourse.;Finally, the characteristics of SIMOF and comparison with other ontology modularization frameworks are discussed.