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RE: reference needed (URIs and what they refer to)

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Thu, 5 Jun 2003 09:38:26 +0200
To: "www-rdf-logic" <www-rdf-logic@w3.org>
Cc: "tm-pubsubj" <tm-pubsubj@lists.oasis-open.org>
Message-ID: <PHENKPMFEPGEMOCCHNFPEEMGCCAA.bernard.vatant@mondeca.com>


Dan

Thanks for the link. To complete my previous post, I would add that your
original diagram at
http://www.w3.org/2003/02/06-tag-summary#httpRange-14
is exactly isomorph to the schema PSI specification propose. Just a
question of matching vocabularies.

In your diagram:

URI ---> identifies ---> Resource
Resource ---> is represented by ---> "bag of bytes + media type"

Matches the following schema in PSI terminology. Remember "Subject" is the
Topic Map term for RDF "Resource".

Subject Identifier (URI) ---> identifies ---> Subject
Subject ---> is indicated by ---> Subject Indicator

I guess "indication" and "representation" are the same here. It is for
human consumption, to figure what the Subject-Resource *is" ... Maybe PSIs
prose would be more understandable in RDF land if translated in the term of
the TAG diagram, like the  following

Subject :: Resource
Subject Identifier :: Resource Identifier
Subject Indicator :: Resource Representation

With that vocabulary we could rewrite all our specification and see how it
flies. Since Identifier and Representation have different initial, we would
get rid of acronym ambiguity with PRI and PRR ...

Bernard


> -----Message d'origine-----
> De : www-rdf-logic-request@w3.org
> [mailto:www-rdf-logic-request@w3.org]De la part de Dan Connolly
> Envoyé : jeudi 5 juin 2003 06:20
> À : Lynn Andrea Stein
> Cc : Sandro Hawke; www-rdf-logic
> Objet : Re: reference needed (URIs and what they refer to)
>
>
>
> On Wed, 2003-06-04 at 16:15, Lynn Andrea Stein wrote:
> > > Resent-From: www-rdf-logic@w3.org
> > > From: Sandro Hawke <sandro@w3.org>
> > > Date: Wed Jun 4, 2003  3:12:53  PM US/Eastern
> > > To: www-rdf-logic <www-rdf-logic@w3.org>
> > > Subject: Re: reference needed
> > >
> > >> but what if we're using
> > >> an inferencing engine to reason about RDF statements? Would
> the engine
> > >> treat all occurrences of SlashURIs as referring to the thing itself,
> > >
> > > All URIs in RDF refer to things themselves.  Those things themselves
> > > might be web pages.
> >
> >
> > But the URI (e.g., http://www.w3.org/Consortium/) construed in RDF (or
> > RDFS or OWL)  can't simultaneously refer to
> >
> > 1) the bits returned by http get on that particular page
> > AND
> > 2) whatever happens to be the current description of the W3C
> >
> > let alone
> >
> > 3) the Consortium itself
> >
> > etc.
>
> Try looking at it as referring to an agent/object/doodad
> that responds to GET requests with content bits.
>
> Perhaps this analogy helps:
>
> In programs, identifiers refer to variables, which
> have values. In the web, URIs refer to resources
> which have representations.
>
> This is illustrated by the 1st whiteboard diagram from
> the TAG Irvine minutes:
>   http://www.w3.org/2003/02/06-tag-summary#httpRange-14
>
> (the diagrams after the 1st one were explorations
> into levels of detail where there's much less
> consensus).
>
> The 26 March web architecture draft tries to explain
> it; the TAG is leaning toward starting with
> a simpler scenario before introducing the
> fragment identifier stuff. And we're likely to include
> a figure. But perhaps it helps explain... or perhaps
> the readers here can help the TAG tell the story...
> http://www.w3.org/TR/2003/WD-webarch-20030326/#scenarios
>
>
> > In particular, if the bits returned are different tomorrow,
> > interpretation (1) says either the URI still refers to the old bits OR
> > the reference relation has changed -- the URI maps onto a different
> > thing tomorrow
>
> so don't look at it that way.
>
> >  -- while (2) says that the reference relation has
> > remained the same while the referenced object has (internally) changed
> > (its representation).
>
> yes, that's pretty much the idea... most HTTP URIs that
> don't have #s in them work that way; certainly
> http://www.w3.org/Consortium/ does.
>
> >
> > So, while I agree completely that
> >
> > >
> > > I think the RDF Model Theory is very clear that URIs (aka URIRefs)
> > > function in RDF just like constant symbols in classical logic.  No
> > > dereferencing is involved in knowing that each URI acts (within an
> > > interpretation) as a name for something in the domain of discourse.
> > >
> >
> > I've never been quite clear on which the (some)thing(in the domain of
> > discourse) is that the URIRef names.  I suppose that I can use it
> > however I want, but only at the risk of diluting the U -- universality
> > -- in the URI.  And of course all three of (1) the bits returned (2)
> > the (changing) current description and (3) the Consortium are things
> > and so properly nameable by URIs....the question is just *which* URI
> > (or *which* thing).
>
> --
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
>
>
Received on Thursday, 5 June 2003 03:38:46 GMT

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