- From: Frank Manola <fmanola@mitre.org>
- Date: Mon, 22 Apr 2002 09:19:21 -0400
- To: Drew McDermott <drew.mcdermott@yale.edu>
- CC: www-rdf-logic@w3.org
Drew McDermott wrote: > Drew McDermott writes: > > Anyway, the following strikes me as the only reasonable point of view: > > There is simply no way to import part of an ontology, as Sandro and > > Frank both seem to want to do. > > [Sandro] > I'm not sure how I was misunderstood. I think the only reasonable > thing to import is another RDF graph (serialized as some > web-accessible document and named by the web address). > > Hey, I can misunderstand anyone. I was probably accepting something > Frank implied. Well, maybe! Just to clarify (?), I was suggesting "yes" as an answer to: > Does using a term defined by some ontology O in some > RDF graph G mean that G is using O? meaning that G is "using" O if it "uses" some piece of O (the term in question). However, I think I'm agreeing with (both of?) you in wanting to distinguish that situation (picking and choosing) from G "using" (or importing) O in the sense of committing to the entire ontology. > > [Sandro] > So are you committing to some particular web content being served at > the namespace address? That's a difficult issue to get consensus on. > People want to be able to use XML instance data with schemas not on > the web and not necessarily shared. That seems to me like a bad idea > with ontologies, but it's a big problem any XML-namespaces proposal > will run into. > > Unless I'm misunderstanding again, I think we're on the same > wavelength here. There should be a difference between grabbing XML > instance data on an ad hoc basis, and saying, I'm committing to the > claims of yonder ontology. Exactly. But I also think (just to nail this down further) that there should be a difference between grabbing (or referring to by their URIs) RDF or DAML facts (instances) or definitions of terms (which is clearly possible) and committing to *all* the claims of yonder ontology. > > [me] > [example of typical RDF using stuff without importing it] > > But how can a computer see all this? Should it just assume that any > > namespace that expands out to something ending in ".daml" somehow is > > an ontology? This strikes me as a silly tactic for avoiding an > > "imports" declaration. > > [Sandro] > Is it important to you to keep the instance data and the ontology in > separate graphs? I think the Semantic Web is based on merging all the > graphs one believes and can access, so the instances and their > ontologies should not be considered separable graphs. > > No, the graphs aren't separate. But some subgraphs are more equal > than others. For instance, suppose I write a DAML type checker. > Given some instance data, and the ontologies they use, I should be able > to check that the data don't contradict the ontology. (E.g., no one > has two mothers if the ontology says they shouldn't.) Now suppose I > suck in some instance data, and there happen to be some daml > assertions mixed in. It seems to me that without an explict "imports" > statement I would be justified in just taking the instance data that I > wanted (say, with a particular syntactic form) and ignoring the > extraneous daml assertions. > > Hmmm. I seem to contradict myself, given that I want to forbid > picking and choosing pieces of an ontology, but allow exactly that in > other cases. The resolution is that ontology importing seems to be a > distinguished case, which should have a clear syntactic tag. I > understand what it means to import an ontology: take it all. I am > willing to allow for all sorts of other ad hoc cases, but we don't > have to legislate those up front. > > -- Drew McDermott > > > > -- Frank Manola The MITRE Corporation 202 Burlington Road, MS A345 Bedford, MA 01730-1420 mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-875
Received on Monday, 22 April 2002 09:08:47 UTC