Fuzzy Ontologies: State of the Art Revisited

Although ontologies have become the standard for representing knowledge on the Semantic Web, they have a primary limitation, the inability to represent vague and imprecise knowledge. Much research has been undertaken to extend ontologies with the means to overcome this and has resulted in numerous extensions from crisp ontologies to fuzzy ontologies. The original web ontology language, and tools were not designed to handle fuzzy information; therefore, additional research has focused on modifications to extend them. A review of the fuzzy extensions to allow fuzziness in ontologies, web languages, and tools as well as several very current examples of fuzzy ontologies in real-world applications is presented.