- From: Enrico Motta <e.motta@open.ac.uk>
- Date: Sat, 1 Jun 2002 16:30:09 +0100
- To: Jeff Heflin <heflin@cse.lehigh.edu>, WebOnt <www-webont-wg@w3.org>
- Message-Id: <p0510030fb91e95d49d02@[212.126.155.42]>
Jeff, I am not convinced that counting features provides the right metric to assess the distance between OWL-level-1 and Full-OWL. Even assuming that only UnionOf, IntersectionOf and ComplementOf are left out of OWL-level-1 (I agree with your point that hasValue could also be in level 1), Full-OWL wold still remain far more powerful and complex than OWL-level-1. In particular it is a lot harder to implement a system that can reason with arbitrary combinations of unionOf and ComplementOf, than one where you can only say that class A is subclassOf or sameClassAs class B. Vice versa, there are certain features that are trivial to add and would not radically change the nature of a reasoning system for OWL-level-1, such as hasValue. Enrico At 4:55 pm -0400 31/5/02, Jeff Heflin wrote: >Jim Hendler wrote: >> >> Jeff - two points >> >> 1) As I said in my report from WWW, it appears there is a large and >> growing group of users of DAML who are using what might be called >> "thesaurus" systems -- they publish a vocabulary, but the vocabulary >> was created in a different (usualyy proprietary) system. These users >> use something similar to what was in SHOE or RDFS, but they also need >> to express some property restrictions - in particular, it is RDFS + >> unambiguous/unique + sometimes real cardinality. I would venture >> that this is far and away the largest group of current users, and a >> group who OWL Core should support. These are not group 2 >> (description logic) users, and these are people publishing a lot of >> DAML (example, US National Cancer Institute will publish a 40,000 >> term thesaurus updated monthly in D+O subset of this kind) - any >> attempts we make to guess what people will do should certainly >> include this group. > >I was not aware of this group (unfortunately I had to miss WWW), but >agree that we should add it to the list. Without knowing the specifics >of these thesaurus systems, I can't say how for how sure it fits into >the picture, but I imagine that they would not be able to claim level-1 >compatability (as currently defined). In particular, I doubt their >systems can reason with existential local range restrictions and I would >bet that if they use universal local range and local cardinality >restrictions, that they use them as constraints, as opposed to axioms >for drawing inferences (as implied by the semantics of DAML+OIL). This >could be a case to further reduce level-1, or maybe we throw thesaurus >systems in with the "database crowd." > >> 2) I'm not sure what you mean by "almost back at full language" so >> I decided to do the experiment we ran at the f2f -- I took all the >> D+O language features and mapped them against Deb's level 1, and then >> look at the remaining. I believe the following are NOT in level 1: >> >> complementOf >> disjointUnionOf >> disjointWith >> hasValue >> intersectionOf >> oneOf >> onProperty >> unionOf >> >> (which is a significant group). > >I don't believe disjointUnionOf is in consideration for the full >language, and onProperty is just an artifact the RDF serialization of >DAML (it is required for all restrictions). Still, that leaves us with: > >complementOf >intersectionOf >unionOf >disjointWith >hasValue >oneOf > >The first three (complementOf, interectionOf and unionOf) are what I >meant by boolean combinations. Still, that leaves three other features I >didn't realize were left out. I would argue that hasValue and oneOf are >likely to be as widely or more widely used than existential local range >restrictions (hasClass). That certainly appears to be the current case >for DAML+OIL ontologies (see http://www.daml.org/ontologies/features). >So, I would argue if you add local range restrictions, then you should >also add these two as well. Once you do that, then you are getting >pretty close to the full language again. > >> I also suspect that not all of these would go in core - or might be >> otherwise simplified, depending on how our issue re: datatypes > > finally works out: >> >> Datatype >> DatatypeProperty >> DatatypeRestriction >> Datatype value > >If datatypes are done in a similar way, then I expect all of these (or >equivalents) would be in the core. > >> In addition, we haven't discussed whether the "extralogical" things >> we want would also go in core. I expect they would, so I do not >> include: >> imports >> versionInfo > >I would have a major objection if these did not go into the core. > >> I believe the big difference between Core as expressed by Deb and >> Core as proposed at f2f if that at the f2f, we assumed that those 8 >> things not currently in core would be in core for "named" classes. >> Deb's document takes them out of core completely. That seems to me >> to be a very big difference. >> >> -JH >> >> -- >> Professor James Hendler hendler@cs.umd.edu >> Director, Semantic Web and Agent Technologies 301-405-2696 >> Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax) >> Univ of Maryland, College Park, MD 20742 240-731-3822 (Cell) >> http://www.cs.umd.edu/users/hendler
Received on Saturday, 1 June 2002 14:30:23 UTC