@inproceedings{Hirst29,
  author = "Graeme Hirst",
  title = "Ontological assumptions in knowledge representation",
  booktitle = "Proceedings, First International Conference on Principles of Knowledge Representation and Reasoning",
  address = "Toronto",
  month = "May",
  year = "1989",
  publisher = "San Mateo, CA: Morgan Kaufmann Publishers",
  pages = "157--169",
  abstract = "<p>If knowledge representation formalisms are to be suitable for semantic
             interpretation of natural language, they must be more adept with
             representations of existence and non-existence than they presently are. I
             review the philosophical background, and exhibit some ontological problems
             for KR. I then look at the shortcomings of current approaches, including
             several intensional formalisms and the work of Hobbs. The Meinongian theory
             of Parsons is considered. Lastly, I present a na&iuml;ve ontology for
             knowledge representation, identifying about nine distinct kinds of
             existence.</p>"
}