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Re: LANG: Summary of Issues 5.6 and 5.14

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Thu, 19 Sep 2002 17:28:36 -0400
Message-ID: <3D8A4184.6A6A86EF@cse.lehigh.edu>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: www-webont-wg@w3.org

Peter,

You said:

> Jeff's approach allows imports relationships between arbitrary ontologies.
> Pat's approach only allows the importing of another ontology into the
> current situation. 

But that's because Pat's approach is not fully specified. He said "If an
ontology A contains [import B]." If we must express this in RDF, then
the only way is with a triple "A imports B." I would be perfectly happy
with using some other syntax than RDF, and not allowing imports between
arbitrary ontologies, but I did not think that option was on the table.

You also said:

> Jeff's approach requires a notion of ontology in the
> semantics, Pat's doesn't.

But Pat's does require a notion of ontology. What do you think A and B
are? They are ontologies. If you can't mention ontologies in the
semantics, then you can't express his condition. Note that one problem
with Pat's expression is that it uses the symbol B as an identifier for
the ontology and for the ontology itself. My graph() approach
dereferences the symbol to get the ontology.

Finally, you said:

> I think that the difference is, in fact, even greater.  Jeff's approach
> appears to require semantic support.  Pat's approach can be done in the
> syntax.

But we're discussing how we define imports in our documents, not how it
can be implemented. If we say, "If an ontology A contains [import B] (in
whatever notation turns out to be appropriate) and if B + A entails C
then A entails C" in our semantics for imports, then sure there's
syntactic way of achieiving this effect, but I could implement it any
way I wanted to.

Jeff


"Peter F. Patel-Schneider" wrote:
> 
> From: Jeff Heflin <heflin@cse.lehigh.edu>
> Subject: LANG: Summary of Issues 5.6 and 5.14
> Date: Thu, 19 Sep 2002 10:51:18 -0400
> 
> [...]
> 
> > Alternatives:
> >
> > a) An entailment based approach proposed by me [1]. In short, the triple
> > A owl:imports B means if graph(B) entails X then graph(A) entails X
> >
> > Pat Hayes suggested something similar in [2]: "If an ontology A contains
> > [import B] (in whatever notation turns out to be appropriate) and if
> > B + A entails C then A entails C"
> 
> [...]
> 
> I believe that the two approaches above are very different.
> 
> Jeff's approach allows imports relationships between arbitrary ontologies.
> Pat's approach only allows the importing of another ontology into the
> current situation.  Jeff's approach requires a notion of ontology in the
> semantics, Pat's doesn't.
> 
> I think that the difference is, in fact, even greater.  Jeff's approach
> appears to require semantic support.  Pat's approach can be done in the
> syntax.
> 
> peter
Received on Thursday, 19 September 2002 17:28:39 GMT

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