W3C home > Mailing lists > Public > www-rdf-interest@w3.org > September 2004

RE: web proper names

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Mon, 20 Sep 2004 13:18:58 -0400 (EDT)
To: www-rdf-interest@w3.org
Message-ID: <Pine.LNX.4.44.0409201251150.1498-100000@tribal.metalab.unc.edu>

According to the latest URI draft:
"A URI provides a simple and extensible means for identifying a resource"
And under resources: "the term "resource" is used in a general sense for 
whatever might be identified by a URI. Familiar examples include an 
electronic document, an image...a resource iis not necessarily accesible via the Internet; e.g., 
human beings, corporations, and bound books in a library can also be 

All we propose in Web Proper Names is that there is a distinction between:
1) A Representation	 	
2) The Thing Represented (which we call its denotation or referent).

The full paper is at:

Which is already noted by URI and TAG, otherwise they wouldn't feel the 
need to mention these *both* explicitly as "resources".

I do think that this is a useful and needed distinction in Web architecture, 
including RDF. Often the line between a representation and what is represented
 can be blurry, but often it can be quite clear, as in when are  using a 
URI to denote a representation that is intrinsically accessible to the 
Internet (such as web-page, electronic documents, "information resource" 
accoding to TimBL) or when we are using a URI to denote something not
 accessible on the Internet as a representation  (the Eiffel Tower itself, 
bound books, the idea of a human being).  

Yes, a resource can be anything, thus a URI can identify *anything*, but
it would be useful to be able to distinguish explicitly between these 
two types of things (for example, in our previous example, while a human
could read the comments in a RDF Schema or the Dublin Core documentation
to know the correct use of "creator", a machine could not). 

Our proposal builds without any problems on current web use and is not
dependent on RDF, the Semantic Web in general, or the TAG. It takes
something people do everyday - using search engines to find information
about things that are spread throughout multiple represenations - and 
allows users to produce a subjective and useful canonical resource for
that information. This can be accomplished through using a wpn::
URI scheme (As Larry Masinster has also suggested, albeit with less 
context) or with using the Expanded Web Proper Name idea to make such
a canoncial document accesible via the http: scheme. So you can specify a 
thing like Henry Thompson by saying:
terms=Henry\%20S.\%20Thompson\& ln=en\&se=www.google.com\&dt=2004-05-21\&

Or you can make a canonical web-page for something like the Eiffel Tower
Schema, XSL, and a Mozilla plug-in are underway if your interested. E-mail
me if so and I'll e-mail you when the first beta is out (in a month or 

The Semantic Web here, as noticed by many doing Web Standards with a 
background of AI from Pat Hayes to Henry Thompson, is treading on ground 
already treaded on by a good hundred years of work in philosophy and 
decades of work in AI.

Ignorance of these issues led to a serious collapse in AI research a few 
decades back. We, as does everyone here we assume, want the Web and 
initiatives like the Semantic Web to succeed. This is just our 
contribution on this issue.  Other solutions proposed by  Jon (adding a 
way to describe resources relating resources) and Henry (the refers/about 
distinction, which TopicMaps uses I might add) are not necessarily in 
conflict, and I am happy to see people thinking about this distinctions, 
as they have come up in my own Semantic Web work.  I also implore people to think
of useful solutions that are easily implemented, and constructive 
feedback on Web Proper Names is appreciated. If you do not feel this is 
a problem, life will go on - but let us that do work on it.


On Mon, 20 Sep 2004, Jon Hanna wrote:

> > In particular the use/mention distinction has really helped locate a 
> > problem that has kept bugging me when thinking about rdf.
> The analogy is false IMO. Mentioning a URI is saying something like "The
> URI 'http://www.example.net/blah' has 27 characters, uses the common
> convention of naming a webserver 'www', has no query-string and doesn't
> use any of character escapes defined in RFC 2396".
> On the other hand both using a URI to identify a resource and to
> retrieve a representation are using URIs.
> > This can be summarized by considering the following triples which 
> > though formally contradictory, can in fact be seen to be compatible:
> > 
> > (A)     http://www.paris.org/Monuments/Eiffel
> >              http://purl.org/dc/elements/1.1/creator
> >          http://www.gustaveeiffel.com/
> > 
> > (B)     http://www.paris.org/Monuments/Eiffel
> >              http://purl.org/dc/elements/1.1/creator
> >          http://www.endex.com/gf/
> > 
> > If we only understand the above names to be used then the two 
> > sentences 
> > are contradictory.
> > 
> > (A) states that the Eiffel Tower was created by Gustav 
> > Eiffel, whereas 
> > (B) states that
> > it was created by Gary Feuerstein. (A) is true in this 
> > interpretation, 
> > whereas (B) is false.
> > 
> > But we can guess that what was probably intended by (B) was not that 
> > <http://www.paris.org/Monuments/Eiffel> refer to the Eiffel 
> > Tower, but 
> > that it refer to the Web Page which refers to the Eiffel 
> > Tower, whereas 
> > in the first sentence we have the intuition that it refers to the 
> > actual building located in Paris.
> We can guess what was meant by a lot of incorrect statements, they are
> still incorrect though.
> Actually it could be that A is correct and B is incorrect - it is
> perfectly reasonable for URIs to identify the kind of "conceptual
> document" that the HTTP-URIs-are-limited camp say all URIs identify
> (sometimes a cigar is still a cigar). Neither possibility for what
> http://www.paris.org/Monuments/Eiffel identifies is problematic though.
> There is a clear relationship between the document and the monument in
> either case: All we need is some sort of framework for describing
> resources which defines relationships between two or more resources.
> Preferably those relationships would be identified with URIs to keep it
> all webby and RESTful. Maybe something using a labelled acyclic graph
> might be the way to go about it...
> > Harry's solution is to assume that rdf resources by default point to 
> > the representation of the resource and not the thing itself, and then 
> You can't even assume that a resource has a representation, or that
> there is only one. Assuming that this is what is being referred to is
> hence falls long before the first fence.
> (Also, I dispute the use of the term "rdf resources". There are
> resources. RDF is a way to describe them.)
> > to add a new wpn:// scheme to help create names that refer 
> > directly to 
> > an object.
> It follows from the argument that URIs don't identify resources that we
> need some sort of uniform resource identifier. I don't buy the problem,
> so I don't buy the solution.
>  It occurs to me right now that from a philosophical 
> > perspective this cannot quite be the correct solution, since the 
> > arguments have always been that names can be used in both ways.
> I've hardly ever heard this argued. What I have heard argued is:
> 1. URIs identify any sort of thing. When used with a given system (the
> web) they result in representations being returned. When used otherwise
> the system in question does whatever is appropriate for it to do with
> respect to that thing.
> 2. URIs identify "conceptual documents". When used with the web they
> result in a particular document being returned, which in regards to such
> matters as content-type, language and other negotiable features is an
> instance of the more Platonic "conceptual document" (which is not in a
> particular language or content-type).
> Just because you get a representation when you do a particular action
> with it no more makes that representation the thing the URI identify
> than using my name in an enquiry makes "Jon Hanna" intrinsically bound
> to "Quite tall, shaven head, wears black a lot". It certainly doesn't
> make it bound to that and nothing else.
> > Would it perhaps not be easier to extend RDF so that one can 
> > point to a 
> > resource in either way, for example by allowing the following:
> > 
> > <Entry rdf:about="http://www.paris.org/Monuments/Eiffel">
> > or
> > <Entry rdf:refers="http://www.paris.org/Monuments/Eiffel">
> That isn't extending RDF, it's extending RDF/XML. I think the way to
> extend RDF to deal with this is to define a predicate that defines the
> relationship between the resource identified by the URI and the zero or
> more representations that may be returned when you dereference it's
> URIs.
> (Amusingly one could usefully mention URIs for real here since a
> resource can have more than one URI, but the representation returned may
> depend on which one is used - this is a feature of the character strings
> the webserver received, not of the URI qua resource identifier.)
> > I have been confused a few times about this exact problem, 
> > and am very 
> > thankful to Harry Halpin, and Henry S.Thompson for the clear 
> > explanation of this problem.
> I think the waters are muddier now.
Received on Monday, 20 September 2004 17:22:23 UTC

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