W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > April 2003

Re: URGENT: train wreck coming, action needed. (was: Fwd: URI-CG group chartered)

From: Frank Manola <fmanola@mitre.org>
Date: Fri, 04 Apr 2003 17:31:40 -0500
Message-ID: <3E8E07CC.8020408@mitre.org>
To: pat hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org

pat hayes wrote:

> (Im CCing this to people outside the RDF Core WG as the issue is much 
> larger than just for RDF.  Please be selective in CCing replies in order 
> to avoid cross-list postings, thanks. -Pat)

I'm restricting this to RDF Core.

>> Date: Tue, 01 Apr 2003 19:30:47 +0100
>> To: w3c-rdfcore-wg@w3.org
>> From: Graham Klyne <gk@ninebynine.org>
>> Subject: URI-CG group chartered

>> FYI, the URI CG is now officially chartered.
>>   URI Coordination Group
>>   http://www.w3.org/2001/12/URI/
>> "The mission of this group is to coordinate ongoing work in the area of
>> Uniform Resource Identifiers (URIs); to serve as a coordinating body of
>> all issues involving URIs in the W3C and act as the coordinating body
>> for URI issues with other groups.
>> ...
>> Back in the mists of 2002, I volunteered to act as RDFcore liaison for 
>> this group.
>> As yet, there's been little activity.  It might be worth noting that 
>> Roy Fielding is working on a revision to RFC2396 (version available 
>> at: http://www.apache.org/~fielding/uri/rev-2002/rfc2396bis.html).
>> The IETF URI BOF (a week or so ago) also had some discussion or IRIs.
>> There were a couple of things raised at the IETF meeting that may be 
>> of relevance to RDFcore:
>> (1) a suggestion that "resources" don't exist unless a URI is defined 
>> for them.  (I raised an objection to this --because we have bnodes-- 
>> which was somewhat brushed aside with "If RDF has a problem with URIs 
>> its RDF's problem not URI's problem.  Since the matter is more 
>> philosophical than of practical import, I don't think it's a big deal.)

Pat's objections seem well-taken to me.  But I'd like to describe this 
from a slightly different perspective (or maybe it's the same 
perspective, but a different vocabulary).  If I take the "Semantic Web 
is making the Web like a giant database" analogy, it seems to me that 
saying that a resource doesn't exist (in the Web) unless a URI is 
defined for it is like saying that a resource doesn't exist (in a 
database) unless there's a row for it:  say, in a "Resources" table.  Or 
if you like more specific examples, saying that a Person doesn't exist 
unless there's a URI defined for it is like saying that a Person doesn't 
exist unless there's a row defined for it in the database's Person 
table.  Among other things, this seems like the mother of all closed 
world assumptions.

> But this IS a VERY big deal, and we should raise hell about it, and not 
> stop raising hell until this idea is abandoned. This decision would be a 
> disaster not just for RDF but for almost any web logic. It would force 
> all web logics to treat resources as temporal entities which come into 
> existence at a time (and maybe go out of existence and reappear later). 
> This plays havoc with ALL quantified logics, not just RDF.  It 
> effectively makes all current mechanical reasoners invalid (since they 
> all use, one way or another, the principles underlying existential 
> quantification.) It also plays havoc with all semantics for NL dialog 
> and just about everything else.  It would drive a truck through all 
> assertional datatyping and most attempts to do syntax layering (such as 
> the OWL/RDF mappings and any future son-of-OWL/RDF mappings.) It is not 
> just an obscure philosophical niggle: it is absolutely fundamental.
> For one (tiny) example of the trouble it would cause, try making sense 
> of this idea in the context of a URI scheme for identifying dates and 
> times. If nobody has perviously mentioned 3.48 am on the 24th of 
> February, 1865, does that date suddenly come into existence at the time 
> someone one first mentions it with a URI? What if someone has mentioned 
> the year 1865? Did that particular year have a minute-length hole in it, 
> which has just gotten filled in? Don't laugh when your temporal reasoner 
> figures out that you don't need to get to the airport until a minute 
> after the flight leaves.
> This group needs to pay some serious attention to what it is talking 
> about. Fielding's draft cited above repeats verbatim the extremely 
> grandiose and rather wooly text from RFC 2369 claiming that 'resources' 
> are anything that can possibly exist, on the web or off it.  It is 
> irrational and incoherent to assert this and also treat resources as 
> though they were datastructures or computational constructs of some 
> kind.  If the group's attitude to issues like this is that these are 
> just philosophical niggles of no real consequence, then the best thing 
> this group could do would be to disband itself before it does more harm, 
> or at the very least try co-opting someone who knows something about 
> what the issues are here. URIs are too important to be left to 
> syntactical engineers.
> Pat Hayes

Frank Manola                   The MITRE Corporation
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mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-875
Received on Friday, 4 April 2003 17:10:54 UTC

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