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

Hi Pat,

Here's how I see it (discussing things we can't see again).

On a universal scale (as in giant global graph) we have a set of nodes, 
each node is associated with one or more unique names, and one or more 
propositions. Each node can be seen as having a 1-1 relation with a 
single distinct thing (whether real or abstract), and the set of 
propositions bound to that node can be seen as characterizing (not 
defining) the thing which the node is related to. Exactly what those 
propositions characterize is open to interpretation, and when you're 
only working with subsets of the global graph (as is the norm) what the 
node is interpreted as characterizing gets increasingly less specific 
ever more ambiguous.

If we split the previous paragraph in half, then by looking at only the 
first half we can argue that each name has at most one referent, and 
each thing can have multiple names (a many-1 relation). If we look at 
the second half then we can argue that each name can have multiple 
referents, and each thing multiple names (a many-many relation).

An application may not need to consider or know every property of a 
thing to answer the question it is being asked, and may not need to (or 
be able to) make distinctions between unique things.

So, to what does a name refer?

To me it is important to view each name as having at most one referent, 
then if you tell me that you interpret the name as referring to 
something else, I can offer some more propositions and refine my 
description, in order that we may collectively describe the world and 
hopefully start to understand each thing.

So, whilst I understand that the distinctions don't always matter, and 
that it's generally nigh on impossible to define a thing unambiguously, 
I still feel it is critically important to view each name as having a 
single referent, and to view each name as identifying a unique thing, 
unless told otherwise (by proposition or inference).

in-line:

Pat Hayes wrote:
> On Mar 20, 2011, at 10:30 AM, Nathan wrote:
>> This is why we couple descriptions to names, to give an indication of what we are using a name to refer to, sure our descriptions may be ambiguous and open to refinement, but our names are not; because we are not using simple string token names "everest" or "lightbulb", we're using distinct URIs.
> 
> So, are you saying it is the *syntax* of URIs which gives them this magical quality? So one gets unambiguous reference by putting a colon in the name somewhere?  OK, forgive my sarcasm: but if this is not what you are saying, just what ARE you saying, that gives URIs this amazing ability to reach out into the world and seize upon their single unique referent?

The point I was trying to make (badly) was two fold:

1: Rather than saying "when I say X I mean this" and "when you say X you 
mean that" (where this != that) as humans with limited vocabulary often 
do. We can instead use URIs with gives us a wider vocabulary and greater 
opportunity to have one or more unique names for each referent.

2: The magical quality is in the specs and a social agreement, that we 
will typically consider each URI as having at most one referent, thus 
allowing us to say that each URI unambiguously identifies a single 
thing; even when the interpreted characterization of that thing is 
ambiguous.

>[snip]
>> So, I have to conclude that the names aren't ambiguous here
> 
> What would lead you to that conclusion? I don't see that you have argued for it anywhere. Like TimBL's claim, it seems to be a matter of W3C Dogma rather than an actual observation or even a rationally defended position. And as it is radically false, and indeed in many cases *provably* false, it seems rather obtuse to be defending it with so slender an excuse or argument. 

Hopefully the above helps explain my own personal thinking on it, well 
as well as I can understand things given my limited knowledge.

Best,

Nathan

Received on Wednesday, 23 March 2011 01:13:25 UTC