Re: Coordination with RDF Core

From: pat hayes (
Date: 07/09/01

>pat hayes wrote:
> > I would like to see the 'URI' point retained in the document. The
> > more the coreWG gets its node rubbed in this issue, the better :-)
>The URI point from Peter's notes stated:
> >  - what is a URI? - syntax and semantics
>URI syntax is specified in by Tim et al.
>so I don't really see the substance of that part of the complaint.
>(The RFC describes the syntax that is common to all URI schemes,
>and the scheme-specific details of the syntax are/should be specified
>in other places, seems reasonable to me).
>Concering semantics, the same document says:
>"A Uniform Resource Identifier (URI) is a compact string of characters
>   for identifying an abstract or physical resource."
>I've always understood that URI's are simply globally unique names,

Right. But this isnt yet sharply enough defined. Do you mean 'logical 
names' (ie constant symbols), or something more like 'names' in NL? 
The discussions surrounding the notion of URI often seem to blur the 
two. Also , consistently says 
that URI's are a  "means for identifying" a resource, and this 
innocent-seeming phrase hides a huge array of assumptions. File names 
for example provide a means to identify their files in a way that 
personal names do not identify the people they name, and personal 
names (and public names more generally) identify people (and cities, 
etc.) in ways that logical 'names' do not, and probably cannot 
possibly, emulate. Merely denoting something is not like being able 
to pick it out from a police line-up. So my conclusion is that this 
apparently technical area is in fact a mass of confusion and unstated 
assumptions, some of which are widely understood (but not widely 
agreed on) and others not properly discussed anywhere.
Finally, even if we take the very restrictive view and say that URI's 
are just logical constants with an odd syntax (required to avoid 
global name-clashes), then the question arises as to what the 
nonlogical vocabulary of a language like RDF or DAML+OIL is supposed 
to be? Validity has to be understood relative to a particular 
vocabulary. We have had some very confused exchanges on RDFCore 
recently about whether RDF 'anonymous' nodes are like existential 
varaibles, for example, which have gotten confused partly because 
folk do not realize that skolemisation is not valid because it 
changes the logical signature.

>(which I think is pretty much what Tim's RFC says). In terms of our 
>model-theoretic semantics, are URI's not simply the elements of AD, 
>and that's it?

Certainly not, in most interperations. (One in which the elements of 
AD were URI's would be the DAML equivalent of a Herbrand 

>So I felt unsure as to what really the substance of Peter's point was.
>I also reread much of the discussion on URI's on rdf-logic, back in April
>(starting from 
>but I found the whole discussion rather unilluminating (then, and 
>now again), mostly by folks suffering from a severe case of 
>use\mention confusion.

Right, and that is another issue I would like to rub the WG's node in.

>Pat, can you expand on what exactly the coreWG should get its nose 
>rubbed into?

See above.


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