From the “10 years of keetblog – reblogging: 2010”: two solid papers on the feasibility of rough ontologies, presented at DL’10 (logic stuff) and EKAW’10 (ontology engineering aspects). Short answer: not really feasible from a computational viewpoint. Notwithstanding, I did give it a try afterwards with ‘rOWL’ (SAICSIT’11 paper) before giving up on it, and other people do try, too (see citations of the DL and EKAW papers).
Rough ontologies from an ontology engineering perspective, June 14
Somewhere buried in the blogpost about the DL’10 workshop, I mentioned the topic of my paper  at the 23rd International Description Logics Workshop (DL’10), which concerned the feasibility of rough DL knowledge bases. That paper was focussed on the theoretical assessment (result: there are serious theoretical hurdles for rough DL KBs) and had a rather short section where experimental results were crammed into the odd page (result: one can squeeze at least something out of the extant languages and tools, but more should be possible in the near future). More recently, my paper  submitted to the 17th International Conference on Knowledge Engineering and Knowledge Management (EKAW’10) got accepted, which focuses on the ontology engineering side of rough ontologies and therefore has a lot more information on how one can squeeze something out of the extant languages and tools; if that is not enough, there is also supplementary material that people can play with.
Ideally, they ought to go together in on paper to get a good overview at once, but there are page limits for conference papers and anyhow the last word has not been said about rough ontologies. For what it is worth, I have put the two together in the slides for the weekly KRDB Lunch Seminar that I will present tomorrow at, well, lunch hour in the seminar room on the first floor of the POS building.
 Keet, C. M. On the feasibility of Description Logic knowledge bases with rough concepts and vague instances. Proc. of DL’10, 4-7 May 2010, Waterloo, Canada. pp314-324.
 Keet, C. M. Ontology engineering with rough concepts and instances. 17th International Conference on Knowledge Engineering and Knowledge Management (EKAW’10). 11-15 October 2010, Lisbon, Portugal. Springer LNCS.