From W3C Wiki
Jump to: navigation, search

Possible Notes for OEP Task Force of SWBP WG

Ontology Patterns

  • [CW] The partOf relation. There really isn't that much that can be "said" in OWL (and therefore less in RDF) regarding the typical axiomatizations of partOf, but knowing the different kinds of partOf relations and what they are supposed to mean would be useful. I'm hoping that some subset of Nicola, Alan, and I can take the lead on this one, but I also see the need for a couple of notes here, so I think this needs further discussion.
    • [EW] a note that would contain some sample OWL, not just text. This would boot-strap new users of OWL on some simple ways to model certain partOf relations. Questions about this come up frequently in places like the Protege-owl list ([1]), and I believe a light note would be very helpful as an intro for domain experts and former UML modelers. Such a note would largely steer clear of philosophical concerns such as reflexivity. I already have created OWL for this and started work on some intro text for such a note. EW lead, DM&AR to help
    • [AR] Notes laying out the classic distinctions, pointing to the the literature on merology, and pointing out things like that most users of partonomy probably want something that is time specific - X is a part of Y at some implied time T (the type is a part of the car now, but it may not be after the tyre has been changed) - or normative (Xs are considered parts of Ys). You need one or the other to avoid getting into issues about amputated fingers, cat's tails, etc. Also I think we have to say that this area is far from settled so we are giving guidance on workable principles plus caveats for controversies.
    • [AR] Implementation mechanisms. Transitive properties for simple things. SEP triples are related trickse. [[RegionOfFrance]] = France or restriction(is_geographical_region_of someValuesFrom(France))]
    • [AR] Property hierarchies showing different relations between containment, location and partonomy.
    • [AR] Also warnings that with current classifiers (possibly excepting FaCT++ but we aren't sure yet) large ontologies containing extensive networks linked by both has_part and is_part_of (or any other transitive relation and its inverse) are potentially combinatorially explosive. If anybody does try to use a classifier it is disconcerting to see what seemed to work for a toy run indefinitely for something real.
    • [AR] Transitive properties and part-of - I suggest this as a two part note, the first high priority, the second much lower.
      • Part 1: Transitive properties and one simple part-of relation plus the note that for many purposes we want "Thing or is_part_of Thing" because we don't have reflexive relations. Postscript that part-of is not containment, attachment, membership, etc and comes in different flavours to be covered in a separate note.
      • Part 2: A simple example schema for different kinds of parthood, containment, location, membership, etc. showing the use of the property hierarchy. Were I to do it, I would adapt the scheme in [2] AR to lead
  • [CW] Units and measures. There has been some work on this, including in Cyc, Tom Gruber's ontology in Ontolingua, and Helena Sofia-Pinto did a nice one for the old SUO effort. Evan was interested in this and it certainly makes sense to have someone at NIST do it. Ask WG for volunteers
  • [CW] Subjects. The notion of what a subject "is" and what the "subjectOf" relation means can be quite confusing. I have done a lot of work on this and am willing to take this one on, however I will want to do one at a time. Chris to lead. Longer term
  • [CW] Time. Jerry Hobbs has done a very thorough job putting together a consensus ontology of time based on a lot of existing time ontologies, most of which draw from the Allen calculus. The ontology is expressed in FOL (KIF), but there are (necessarily simplified) DAML+OIL and OWL ("OWL-Time") versions available. Jerry has expressed interest in seeing this as a W3C note. DLM to contact Jerry HObbes
  • [CW] Fluents. Closely tied to the notion of time is being able to say that a binary property "holds" for a time. e.g. one may want to say that "Chris is a member of the W3C from Sept, 2004 - Sept 2005". A property like memberOf is a fluent because it can be said to hold at a time (this is not strictly a correct definition, but it will suffice). While OWL-Time let's you represent a time interval like "Sept, 2004-Sept, 2005", it remains neutral wrt what happens at or during such a time interval. The typical move in FOL is to use a function or add an argument to the predicate, e.g. memberOf(Chris, W3C, time-interval-1), however clearly we can't do that in OWL or RDF, since we are limited to binary predicates. One solution is to go for full reification of fluents, as in the exsiting not on n-ary relations, however there are some other choices. I'm hoping I can get Pat Hayes and Richard Fikes to work with me on this one. Chris to lead. Alan, DeborahM and Evan to comment.

Ontology Engineering

  • [CW] Ontology 101 tutorial specifically for OWL/RDF.
  • [CW] I think a note to help orient people on the role OWL and RDF in semantic integration is critical, I get pinged on that regularly. I lot of people think OWL is the silver bullet for semantic integration (I suggested at ISWC last year that semantic integration is a mountain, not a werewolf, and OWL is, at best, a small silver chisel). There was just a Dagstuhl symposium on this subject in general (i.e. not specific to OWL), and special issues of AI Magazine and Sigmod record coming out as well. I hope Natasha and/or MikeU will take the lead on such a note.
  • [CW] People who know what "ontology" and "semantics" actually mean (in the much larger world outside of computer science), often ask why the two have become nearly synonymous on the semantic web. Personally, I think its a fair question and a short note on why we're so confused would be worthwhile. Maybe this goes in another task force (wasn't there a clean up the mess we've made task force?)
  • [AR] options for using Ontologies in applications - whether in OWL or RDF - this is the thing the SWBP really has to crack. Picking up where Classes as Values left off. I am not sure where pointers to specific tricks with current technology fit in, but in the "deployment" part of SWBP&D I think many people would welcome a list of tool combinations that were known to work, however time limited that list will inevitably be. I am certainly not in a position to produce such a list; I don't think the list per se is really part of OEP, but we need someplace where we coordinate the principles the notes with practice..
  • [AR] When to use a reasoner and normalisation.
  • [AR] I am not sure whether it is a note, but it is worth pointing people at 'common pitfalls'. One contribution towards that is
  • [NN] Numeric ranges -- really, really need this one!
  • [NN] Closing axioms -- without that, classifiers would seldom produce anything useful and if anyone wants to promote the DL abilities of OWL admittedly, I am not one of those people :), you need to tell people how to get even simple things work. Alan has tons of these, in addition to closing axioms
  • [AR] String values - names etc. Also badly needed
  • [AR] Other datatype properties - priority?
  • [CW] Domain and Range restrictions and what to expect, focus on the difference between frames/OO and OWL.