- From: Jeff Heflin <heflin@cse.lehigh.edu>
- Date: Fri, 30 Aug 2002 17:55:13 -0400
- To: Deborah McGuinness <dlm@ksl.stanford.edu>, webont <www-webont-wg@w3.org>
Whoops, here's the footnote: [1} http://www.cse.lehigh.edu/~heflin/pubs/#aaai-02 Jeff Heflin wrote: > > Deborah, > > I've also done some work on a different kind of closed world > information. > In a paper [1] I presented at the recent AAAI Ontologies for the > Semantic Web workshop, I discussed how Oren, Etzioni, and Weld's local > closed world (LCW) information (also called local completeness > information) could be expressed in DAML+OIL. Such information > essentially allows you to say that a particular document has complete > information on the members of some class (for example, American > Airline's website has complete information on all flights by American > Airlines). Although I introduced new syntax to do this, I showed how it > could also be represented using existing DAML+OIL syntax (the key of > course is to use oneOf to enumerate all the instances) and then same > that this is the sameClassAs whatever class expression you want to say > you have complete information for (note, although I didn't catch it > before publishing the paper, the talk I gave at the workshop actually > shows a simpler way to do this than the paper does). > > Jeff > > [1] > Deborah McGuinness wrote: > > > > ACTION: Deb to take a shot at writing up the closed world example > > > > I wrote up a simple example of closed world reasoning in: > > > > http://www.ksl.stanford.edu/people/dlm/daml/closedWorld.html > > > > This just counts the number of values on a property on an individual and > > asserts that maximum cardinality restriction on that property for the > > individual. > > This is the simplest notion of closed world reasoning that we can > > capture. > > I have done some other work (with borgida and hull) on attempting to > > close off an entire individual > > and put the work down a few years ago when it was more complicated than > > we anticipated. > > I will also add a summary of where we left off in a more complicated > > example. > > > > i am enclosing the contents of the url above for archiving purposes for > > the list. > > I used a combination of Guus's how to do it style and my previous tricks > > of the trade style. > > > > d > > > > ========== > > OWL/DAML+OIL "Tricks of the Trade / How To Do It": > > Closed World Reasoning Example > > Author: Deborah L. McGuinness > > > > -------------------------------------------------------------------------------- > > > > Title - Closed World Reasoning. > > > > Task/Modeling problem - Include a notion of closed world reasoning in an > > OWL or DAML+OIL knowledge base. There are many examples of closed world > > reasoning but this example includes two common cases. > > State that the known values for a particular property on a particular > > individual are the only values for that property on that individual. > > Assume for example, that there is an individual instance of the class > > "Person" named "Deborah" with a property "hasCar" with a value > > "Saab900Turbo". The task is to allow a reasoner to infer that Deborah > > only has the saab (and no new distinct individuals will be added as > > values to her hasCar property). > > Observation - DAML+OIL and OWL do not make the closed world reasoning > > assumption, i.e., they do not assume that information that is not known > > to be true is false. They work with an "open world reasoning" > > assumption, i.e., they assume that information that is currently not > > known may become known in the future. Thus, just because Deborah only > > has one known value for a hasCar property does not mean that she may not > > have more cars. Said another way, there is no implicit maximum > > cardinality restriction on Deborah's hasCar property. > > > > Abstracted solution - > > Count the number of values for a property on an individual and then > > assert a max cardinality on that property for that individual. > > > > Example solution - In this particular case, we would add a maximum > > cardinality restriction of 1 on Deborah's hasCar property. This would > > allow reasoners to infer that no additional distinct values for > > Deborah's hasCar property may be added (without first removing the value > > of Saab900Turbo). > > > > Notes - > > > > This solution is the same as the notion of closing a role in the CLASSIC > > description logic. More issues on closing roles can be found in: > > - Ronald J. Brachman , Deborah L. McGuinness , Peter F. Patel-Schneider > > , Lori Alperin Resnick , and Alex Borgida. ``Living with CLASSIC: When > > and How to Use a KL-ONE-Like Language,'' in John Sowa, ed., Principles > > of Semantic Networks: Explorations in the representation of knowledge , > > Morgan-Kaufmann: San Mateo, California, 1991, pages 401--456. > > http://www.ksl.stanford.edu/people/dlm/papers/living-with-classic-abstract.html > > > > -Alex Borgida, Rick Hull, Deborah McGuinness. On the Confluence of the > > Closing Order in Description Logic Knowledge Bases. Working Draft. > > > > -- > > Deborah L. McGuinness > > Knowledge Systems Laboratory > > Gates Computer Science Building, 2A Room 241 > > Stanford University, Stanford, CA 94305-9020 > > email: dlm@ksl.stanford.edu > > URL: http://ksl.stanford.edu/people/dlm/index.html > > (voice) 650 723 9770 (stanford fax) 650 725 5850 (computer fax) > > 801 705 0941
Received on Friday, 30 August 2002 17:55:16 UTC