Re: Valid representations, canonical representations, and what the SW needs from the Web...

[quick, partial reply, on www-archive ]

> Sandro Hawke wrote:
> >...]
> > 
> > In this view, the use of URIs (esp http URIs) in RDF buys us almost
> > nothing but confusion.  At best, it makes looking up some
> > documentation for a term a little easier.  
> 
> Do you consider the RDF schema for a term to be just documentation? I 
> was under the impression that it was a very valuable bit of metadata 
> that could be used in extremely powerful ways by RDF processors.

How do RDF identifiers being http URIs help you with schema
validation?

The URI part of an RDF URIRef has no special status in RDF.  It is
explicitely not the address of a schema or such.  I argued it should
be and lost.


> 
> > ... Really, though, UUIDs or
> > tag: strings would be vastly less confusing and work about as well.
> 
> How would I dereference UUIDs to get what I want? Tag identifiers can be 
> viewed as just a bit of extra syntax around HTTP URIs so of course they 
> are no less powerful. ;)

Tag: identifiers are no more dereferncable than than UUIDs.

In all three cases (http, tag, uuid) you have to find your schema (or
whatever) via extra triples (rdfs:isDefinedBy or owl:imports in the
instance data), or some out of band approach (eg google).  

Oh, maybe if you use a non-fragmwnt URI (like dc: and foaf: ) , then
http GET would be sanctioned.   You imagine http GET on dc:title
should get you the schema?

> > There's an alternative view, however.  Maybe http: URIs are already
> > rather precise.  Each one identifies exactly one web location [1].
> > They can't be used directly to identify the Sun, etc, only indirectly
> > via their content (or using fragment IDs, in one version); that
> > indirect location works just fine for RDF and the semantic web,
> 
> It won't work. You can't know whether "http://www.prescod.net" refers to 
> "Paul's homepage", "The Prescod Family Homepage", "Paul's business", "A 
> set of links endorsed by Paul" etc. unless I tell you. There is nothing 
> in either the URI string nor the document to umabiguously say what that 
> page is about. I can only give it clear, semantic-web processable 
> meaning with RDF. And doing so requires me to make a new URI. So why not 
> use that new URI to represent me?

This is about the social meaning of uris, about people agreeing on
what a uri/symbol means.    Isn't it easier to agree on the observable
qualities of a URI than tose which are by definition in someone's
head?

   -- sandro

Received on Monday, 3 February 2003 22:30:25 UTC