Re: Comments on "SPARQL 1.1 Uniform HTTP Protocol for Managing RDF Graphs"

On Fri, 2011-03-18 at 20:51 +0000, Nathan wrote:
> Here's another quick rewrite:
> David Booth wrote:
> > On Fri, 2011-03-18 at 18:55 +0000, Nathan wrote:
> >>> Can something be both a birth certificate and a red lightbulb? (my intuition says no).
> > 
> > In a given graph g, a URI u can perfectly well (ambiguously) identify
> > something that is both a birth certificate and a red
> > lightbulb, provided that g has no disjointness or other such predicates
> > that would prevent it from being so.
> > 
> > You need to know what graph you are asking about, and what assertions it
> > contains, to answer the question.
> So perhaps the question being answered is, can we feasibly carry out a 
> conversation where we refer to both a birth certificate and a red 
> lightbulb by a single ambiguous name? using RDF?

Yes, if the distinction between birth certificates and red lightbulbs is
irrelevant to our task.

> Possibly, but why even try?


1. Not all applications *need* to distinguish between a lightbulb and a
birth certificate.  For example, an application that cares only about
who owns what may work perfectly fine treating <http://example/#item437>
as an ambiguous combination of a birth certificate and a red lightbulb.

2. Because this kind of ambiguity of reference is *inescapable* (though
the example is an extreme case), so we have no choice but to learn to
deal with it.  

Ambiguity/unambiguity is *relative* to a particular application.  It is
not an absolute notion.  A resource definition that is unambiguous to
one application may be ambiguous to another application that requires
finer distinctions.  In all but vanishingly few cases, it is
*impossible* to define a resource in a universally unambiguous way,
because there are *always* finer distinctions that can be made.  

David Booth, Ph.D.

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.

Received on Friday, 18 March 2011 21:46:02 UTC