M. Klein, A. Kiryakov, D. Ognyanoff, and D. Fensel. European Conference on Artificial Intelligence (ECAI)and Workshop
on Ontologies and Semantic Interoperability, (2002)
R. Studer, V. Benjamins, and D. Fensel. Data & Knowledge Engineering, 25 (1-2):
161--197(March 1998)Definition Ontology (page 25): An ontology is a formal, explicit specification of a shared conceptualisation. A ‘conceptualisation’ refers to an abstract model of some phenomenon in the world by having identified the relevant concepts of that phenomenon. ‘Explicit’ means that the type of concepts used, and the constraints on their use are explicitly defined. For example, in medical domains, the concepts are diseases and symptoms, the relations between them are causal and a constraint is that a disease cannot cause itself. ‘Formal’ refers to the fact that the ontology should be machine readable, which excludes natural language. ‘Shared’ reflects the notion that an ontology captures consensual knowledge, that is, it is not private to some individual, but accepted by a group..
U. Şimşek, E. Kärle, and D. Fensel. Procedia Computer Science, (2018)Proceedings of the 14th International Conference on Semantic Systems 10th – 13th of September 2018 Vienna, Austria.