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?

Because: 

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.
http://dbooth.org/

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