|
I was wrong: it's actually. ontolog-forum@xxxxxxxxxxxxxxxx (should have
looked at the to line!).
Leo
Leo Obrst wrote:
FYI: Mike, this forum is now named ontolog-forum@xxxxxxxx
-- per your message and my reply below. I thought there was an alias, but
I haven't seen it show up.
Leo
-------- Original Message --------
| Subject: |
Re: When are XML Schema and Ontologies Alternatives? $xmls |
| Date: |
Fri, 07 Mar 2003 07:28:57 -0500 |
| From: |
Leo Obrst <lobrst@xxxxxxxxx> |
| Organization: |
The MITRE Corporation |
| To: |
"Uschold, Michael F" <michael.f.uschold@xxxxxxxxxx> |
| CC: |
"Frank van Harmelen (E-mail)" <Frank.van.Harmelen@xxxxxxxx>,"Peter
Patel-Schneider (E-mail)" <pfps@xxxxxxxxxxxxxxxxxxxxxx>,ht@xxxxxxxxxxxxxxx,"Jerome
Simeon (E-mail)" <simeon@xxxxxxxxxxxxxxxxxxxxxx>,"DLU Ontolog (E-mail)"
<ontolog@xxxxxxxxxxxxxxx>,erdmann@xxxxxxxxxxxxxxxxxxxxx,"Rudi Studeri
(E-mail)" <studer@xxxxxxxxxxxxxxxxxxxxx>,"Jones, Janet L" <janet.l.jones@xxxxxxxxxx>,"Moody,
Laura L" <laura.l.moody@xxxxxxxxxx>,"Jones, David H" <david.h.jones@xxxxxxxxxx>,"Thompson,
John A" <john.a.thompson@xxxxxxxxxx>,"Murray, Paul" <paul.murray@xxxxxxxxxxxxxx> |
| References: |
<823043AB1B52784D97754D186877B6CF01E7514C@xxxxxxxxxxxxxxxxxxxxxxxxxxx> |
We've recently been discussing a variant of this question internally
(in MITRE) across two communities, the database and the ontology folks.
I.e., data modeling vs. ontology engineering. I think our point of departure
was the SIGMOD paper from last year:
Data Modelling versus Ontology Engineering. P. Spyns, R. Meersman, M.
Jarrar, Special Section on Semantic Web and Data Management, V. 32:4, December,
2002. http://www.acm.org/sigmod/record/issues/0212/SPECIAL/2.Meersman.pdf.
Note the above requires a login account.
I think the short answer is that database schemas and XML Schema are
a way of structuring data/document collections for some generally local
purpose, e.g., to satisfy an application (or set of applications) or, in
the case of XML Schema, for some generally local exchange of documents/messages.
So, in general, schemas are focused on structure rather than the meaning
of constructs that define that structure. And ontologies address a more
"global" view, in terms of real world semantics.
*However, we all know that structure is the mother of meaning too, that
in fact no semantics is possible without it, and that the formal objects
on the "semantics" side to which the syntax/structures map (in model-theoretic
semantics via an interpretation function) and which we take to "stand in"
for the real/possible world entities whose semantics we want to capture,
are themselves structured (probably because we want those objects to have
certain formal properties, ordering relationships, etc.)
That said, maybe the shortest answer is: A constraint in an XML Schema
is a constraint on the structure or form of a document, not on the meaning
of a real world object as in an ontology.
Leo
"Uschold, Michael F" wrote:
It is not usual for someone to show me an XML shema
and say, "Hey, what do you think of my ontology?", or: "Gee, we are using
an ontology now, but everyone's using XML, so maybe we should use an XML
Schema instead?". Indeed, some people have the impresson that
XML Schema and ontologies** are similar animals and one can use one or
the other for a given problem.
Where does this impression come from?
For SOME problems, ontologies and XML Schema seem for all practical
purposes, to be alternatives. One can create an ontology and a data set
conforming to that ontology, or one could create an XML schema and pass
data conforming to that schema. There would be a clear mapping between
classes and attributes in the ontology and elements and attributes in the
XML schema.
However, I believe that for MOST problems ontologies and XML schema
are not appropriately seen as alternatives, indeed they are quite different
animals for quite different purposes, and can be used to good effect together
complementing each other.
Can anyone resolve this paradox? One great way to answer the question
is like this:
If properties p1, p2, ... pn hold for a given situation, then
for most practical purposes, XML schema and ontologies can be viewed as
alternatives. This is because <now explain how properties p1-pn
make this so, and why when those properties do not hold, the situation
changes and how.>.
What are the properties? I would guess that one has to do with the intended
purpose of the ontology/schema. Related to this would be inference requirements.
Thanks,
Mike Uschold
** For now, lets say by ontology I mean a simple language like OKBC
or even RDFS that one can use Protégé for.
--
_____________________________________________
Dr. Leo Obrst The MITRE Corporation
mailto:lobrst@xxxxxxxxx Intelligent
Information Management/Exploitation
Voice: 703-883-6770 7515 Colshire Drive, M/S H305
Fax: 703-883-1379 McLean, VA 22102-7508,
USA
--
_____________________________________________
Dr. Leo Obrst The MITRE Corporation
mailto:lobrst@xxxxxxxxx Intelligent Information Management/Exploitation
Voice: 703-883-6770 7515 Colshire Drive, M/S H305
Fax: 703-883-1379 McLean, VA 22102-7508,
USA
|