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RE: Inheritance

From: Hans Teijgeler <hans.teijgeler@quicknet.nl>
Date: Wed, 6 Apr 2005 21:42:01 +0200
Message-Id: <200504061942.j36Jg0oj017762@vmx90.multikabel.net>
To: "'Frank Manola'" <fmanola@acm.org>
Cc: "'Jeen Broekstra'" <jeen@aduna.biz>, <semantic-web@w3.org>
Hi Frank,

I think that the real problem lies in the fact that the XML and RDF worlds
are lacking a proper underlying data model.

In the process industries we have worked for 15 years on a generic, 5NF,
data-driven  <http://www.infowebml.ws/ECM4.5/ECM4.5.html> data model that is
advanced enough to model the lifecycle information of facilities like a
refinery or oil well. "Lifecycle" for an oil well easily means 100 years, so
we needed something solid and not the gizmo-of-the-day. We first model the
information and then find a way to exchange and integrate it in what is the
leading technology at that moment.

For us your triple  "ex:Volkswagen dc:creator ex:Frank" cannot be true at
all, because a class in our terminology is: "A class is a thing that is an
understanding of the nature of things and that divides things into those
which are members of the class and those which are not according to one or
more criteria.". It is an abstraction that has always existed and will
always exist, and therefore cannot be created. It may not have members and
it may not yet have been discovered, but it was there starting with the Big
Bang. So the class "Volkwagen" was there already before there were even
human beings. Quite a paradigm shift, I guess! The physical_object
"myVolkswagen" was created by the VW factory somewhere in this world, and it
meets the criteria for membership of the class "Volkswagen". (Note: "A
physical_object is a possible_individual that is a distribution of matter,
energy, or both." AND: "A possible_individual is a thing that exists in
space and time.")

Another thing that I read in the RDF Primer and that I read here again keeps
amazing me. That is the assumed possibility that it cannot be discriminated
whether a reference is to a thing or to its description. In my world the
record about a thing has a UID and the description of the thing, being an
instance of a totally different entity data type, has a different UID. No
confusion possible, ever.
So returning to your example: "ex:Volkswagen dc:creator ex:Frank" would read
in our lingo (the format is free-format):
class_of_inanimate_physical_object"Volkwagen"  is_represented_by a
class_of_information_representation"Volkswagen catalog"
class_of_information_representation"Volkswagen catalog" is_defined_by
About your remark on XML Namespace: we don't use them other than for
references to schemas. The standard ISO 15926-7 that I wrote uses XML Schema
in a rather unusual manner, where we make reference to identifiers that are
not necessarily inside the same XML document (sounds RDF-ish!). Click here
if you want to see how I tried to map this to RDF.
The strange experience with the XML Schema forum was that I have never
understood what the end products of the, undoubtedly serious, efforts of the
other subscribers was. And to some extent I have that experience somewhat
already with the semantic web scene. My colleague Onno Paap of Fluor Corp.
complained to me that he was unable to find out (for RDF and OWL) where "the
rubber meets the road". But we keep trying.
Thanks for your help!

-----Original Message-----
From: semantic-web-request@w3.org [ <mailto:semantic-web-request@w3.org>
mailto:semantic-web-request@w3.org] On Behalf Of Frank Manola
Sent: woensdag 6 april 2005 17:34
To: Hans Teijgeler
Cc: 'Jeen Broekstra'; semantic-web@w3.org
Subject: Re: Inheritance

Hans Teijgeler wrote:

> As to the browser subject: I read, much to my surprise, in Appendix A
> of the
> Primer: "...RDF uses URIrefs only to identify things, while browsers
> also use URIrefs to retrieve things." I was surprised, because why on
> earth would you use a "Resource Description" Framework without being
> able to find that description? So, a browser should be able to find
> the resource at its URI, and then give me the information about that
> resource that I require. Again, too na´ve, I guess.

You certainly want to be able to find the description.  RDF simply doesn't
say anything about whether you can find it by dereferencing the URIref as a
URL.  There's been (and continues to be) a lot of discussion about a
generalized way to retrieve information about a given resource, since many
people prefer not to confuse the name of the thing with the name of its
description by using the same URIref for both.  After all, you may want to
provide RDF descriptive information about the description itself.  For
example, does the statement

ex:Volkswagen dc:creator ex:Frank .

say that Frank created the Volkswagen referred to by ex:Volkswagen, or that
Frank created the descriptive information that you might be able to retrieve
from ex:Volkswagen?

Since you said you've been working with XML, note that XML namespaces work
in a similar way.  That is, an XML namespace is identified by a URIref, but
there is no requirement that any kind of descriptive information about the
namespace is retrievable at that URI.

Received on Wednesday, 6 April 2005 19:42:20 UTC

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