W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2001

Re: Model-specific identity for anon resources, and its representation: A new issue?

From: pat hayes <phayes@ai.uwf.edu>
Date: Sat, 23 Jun 2001 23:22:15 -0500
Message-Id: <v04210106b759e276e3bd@[205.160.76.176]>
To: Sergey Melnik <melnik@db.stanford.edu>
Cc: w3c-rdfcore-wg@w3.org
>Dan Brickley wrote:
> >
> > On Fri, 15 Jun 2001, Aaron Swartz wrote:
> >
> > > On Friday, June 15, 2001, at 06:10  PM, Sergey Melnik wrote:
> > >
> > > > I don't agree that anonymous nodes should be part of the abstract
> > > > syntax, and would suggest to consider this issue when cleaning up the
> > > > model.
> >
> > I disagree: it is critically important to distinguish between well known,
> > public URI names for things and ad-hoc generated placeholder IDs that have
> > been dreamt up by an RDF/XML parser. Unless the abstract syntax (or
> > whatever we call it) maintains that distinction, we risk getting into a
> > terrible muddle.
> >
> > > I tend to agree with this position. However, I would take it one
> > > step further -- I believe that these "uniquely generated
> > > resources" should have consistent, repeatably generated URIs.
> > > That is, all parsers should assign the same genid to the same
> > > resource.
> >
> > do you really mean this last claim?
> > I suspect you meant that all parsers should assign a predictable genid
> > given a common RDF/XML description mentioning a resource. 'all parsers
> > should assign the same genid to the same resource' would be magic, since
> > many times parsers won't have that information accessible.
>
>Dan,
>
>just to provide a pointer, a whole while ago I proposed an algorithm for
>doing exacty that "magic". A summary of the proposal can be found at
>http://nestroy.wi-inf.uni-essen.de/rdf/sum_rdf_api/ under "URI
>generation for anonymous resources" (by Peter Hannappel and Reinhold
>Klapsing). I believe, if needed, this algorithm can be tweaked to
>eliminated the problems wrt using XOR (as pointed out by Brian long
>ago).
>
>I still think anonymous resources first need to be resolved as a model
>issue. Then, we can move to the syntax. BTW, well-known public names
>introduce another danger, which can be even more malicious that
>generating ad-hoc URIs: if I'm using danbri@w3.org as an identifier for
>Dan's email address, and (mis)using for identifying Dan himself, I can
>get into a worse trouble as compared with using two ad-hoc, not as
>well-known, but sufficiently unique URIs that allow me to distinguish
>that I'm dealing with two separate entities. When I have two different
>resources, they still may turn out to represent the same thing. In
>contrast, if I'm using a single resource for representing several
>different things, I'm in a bigger mess.

Sergey, can I use your message as an excuse to raise another basic issue.

I gather that 'resource' means 'entity', ie anything is a resource. 
In this picture, then, the resources are the things in the universe 
that RDF is talking about, ie that RDF expressions refer to.  But you 
use a terminology in which the resources do the referring, ie the 
resources are REPRESENTING entities, rather than being the entities 
that are represented. So again, I am confused what is meant. When you 
talk of resources representing entities, what kind of things are 
'resources', and how do they represent?

BTW, I agree about the complexities that arise from the idea of 
'public names', and the need to get these into the open. This is the 
place, IMO, where an RDF semantics is going to need most work.

Pat

---------------------------------------------------------------------
IHMC					(850)434 8903   home
40 South Alcaniz St.			(850)202 4416   office
Pensacola,  FL 32501			(850)202 4440   fax
phayes@ai.uwf.edu 
http://www.coginst.uwf.edu/~phayes
Received on Monday, 25 June 2001 10:43:15 EDT

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:37:16 EDT