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Re: silly question about rdf:about

From: Lars Marius Garshol <larsga@garshol.priv.no>
Date: 03 May 2002 23:45:48 +0200
To: www-rdf-interest@w3.org
Message-ID: <m3sn58q50z.fsf@pc36.avidiaasen.online.no>

* Lars Marius Garshol
|
| There isn't a whole lot of RDF out there,

* Uche Ogbuji
| 
| Surprising statement, but anyway...

Let me rephrase, then. :)

There isn't a whole lot of RDF out there, that I have been able to
find, but pointers to RDF data would be very much appreciated. In
fact, I've asked for pointers several times, but have had few replies,
so I assume there isn't all that much out there.

Formal investigations have arrived at much the same result:
  <URL: http://www.i-u.de/schools/eberhart/rdf/rdf-survey.htm >
 
I am not saying, BTW, that "there is much more topic map data than RDF
data on the web" (there isn't), or that "RDF has failed because there
is no RDF on the web" (it hasn't, and people don't tend to publish
data anyway, in any form (other than HTML)).

I am just saying that it looks as though there isn't that much RDF
data on the web, and that I'm unhappy about this, as I would have
liked to see more of it.

| Wait a minute.  What are we arguing here?  Just because they are
| using HTTP URIs does not mean they are making an unreasoned stand in
| for an entity.  My point has been that as long as there is agreement
| on the matter, there is no reason why an HTTP URI cannot stand in
| for an abstract entity.  It is then no more than any other name.

I see what you mean, but what you lose then is the ability to speak
both about the resource and about the thing for which you are using
its URI as a name. (Difficult sentence, I know. Sorry.) Other than
that it works fine.

This is why I think published subjects can work both for topic maps
*and* for RDF. If there were RDF people in the PubSubj TC we could
even make sure that they would. 
 
| You seem to agree, based on the fact that you gave an HTTP URI as an
| example of a published subject indicator (indicator, right?).

No. I use the URI to identify a resource, and I use the content of the
resource to identify an abstract entity. It is always clear that what
is being identified is the abstract entity described by the resource,
even if the URI happens to point to a resource. (In fact, the URI is
required to point to a resource, since all subject indicators are
resources.) The reason it is clear is because there are three kinds of
URI references attached to topics:

 - one kind that refers to a resource that *is* the subject,

 - one kind that refers to a resource that *describes* the subject,
   and 

 - one kind that serves as an identifier for the topic.

The Standard Application Model describes all this:
  <URL: http://www.y12.doe.gov/sgml/sc34/document/0299.htm#N483 >
 
Unfortunately, the tutorial prose is not written yet, but it may be a
help anyway.

| Back to the original example.  If I see
| 
| http://uche.ogbuji.net
| 
| Then it is unreasonable for me to think, of my own, that it means
| anything other than the Web site that is to be found there.  If,
| however, you and I have agreed that this URI is a stand-in for the
| person, then we can proceed to use it as such.
| 
| Isn't this *exactly* how PSIs work?

Nearly, but not quite. When you make the URI a PSI representing you
what you say is

  "we agree that this URI identifies a resource, and that that
  resource contains something (text/image data/whatever) that
  identifies Uche Ogbuji to a human being"

It is still possible to speak of the resource with the exact same URI
without anyone confusing the resource with Uche. Look at my other
email (the one you didn't reply to, presumably because you didn't have
time). It explains this in more detail.
 
| Possibly, the examples you give are not explicit enough about the
| meaning/intent of their URIs.  If so, that is bad practice, but the
| sort of bad practice that is common with any naming system.

What did you mean by this?
 
* Lars Marius Garshol
|
| So what? Confusion is confusion, no matter where it comes from.
 
* Uche Ogbuji
|
| Are you implying that people cannot build bad models with TM?

Are you implying that I'm mad or bigoted? :)

Of course they can, I'm just saying that confusion is bad. You said
that "if people are confused about this it's not RDF's fault". My
point was that whose fault it is is not that interesting.
 
* Lars Marius Garshol
|
| Yes and no. The meaning of http URIs is crystal clear, but their use
| in RDF is anything but. The discussions going on in the RDF community
| right now show that there is nothing like consensus on whether RDF may
| or may not use them to refer to things that are not
| network-retreivable, even if it is obvious to all concerned that what
| one gets by resolving an http URI *is* network-retreivable.
 
* Uche Ogbuji
|
| Which discussions do you refer to, in particular?

The "Documents, cars, hills, and valleys" discussion on this mailing
list is one example.

-- 
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
ISO SC34/WG3, OASIS GeoLang TC        <URL: http://www.garshol.priv.no >
Received on Friday, 3 May 2002 18:40:11 GMT

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