W3C home > Mailing lists > Public > semantic-web@w3.org > June 2007

Re: owl:sameAs use/misuse/abuse Re: homonym URIs

From: Dan Brickley <danbri@danbri.org>
Date: Thu, 14 Jun 2007 12:17:20 +0100
Message-ID: <467123C0.80200@danbri.org>
To: Bernard Vatant <bernard.vatant@mondeca.com>
CC: semantic-web@w3.org

Bernard Vatant wrote:
> 
> Just to hit this owl:sameAs (ab)use nail a bit more.
> 
> Although I agree with Pat below (see my previous message) suppose I (or 
> Richard) disagree(s) and want(s) to stick to the assertion
> http://dbpedia.org/resource/Berlin owl:sameAs 
> http://sws.geonames.org/2950159/
> 
> Does that mean that what I get from the two resources should be not only 
> consistent RDF descriptions, but *identical descriptions* ? I guess so. 
> It's clear that it's not the current case.

The point is, according to the owl:sameAs claim, there aren't two 
resources, just one. One thing - with (at least two names (URIs). Asking 
an information system (such as the Web itself, or a library catalogue) 
about this thing could reasonably elicit different answers, depending on 
which name is used. That doesn't mean there are two things.

Similarly, in the real world, different people and info systems known 
different things about me; they may even consider me to have different 
names/URIs. But there's only one me. And so, anything true of me, is 
true of me. Some things might be true of one of my *names* (eg. that it 
is mentioned in a particular database). So yup, owl:sameAs is a pretty 
strong claim. Anything true of the one should be true of the other; 
because there is just the one.(*)

Whether an HTTP GET that returns a 200 should always return the same 
thing, ... is an interesting question. It's certainly (if we believe the 
HTTP responses, and we believe the owl:sameAs claim) supposed to be 
considered an interaction with the same thing. But plenty of URIs return 
different or random or context-specific responses. 
http://spypixel.com/2006/spanglish/futurebot.cgi names the self-same 
resource as http://spypixel.com/2006/spanglish/futurebot.cgi (not 
becaues of owl:sameAs, but because it is the same URI :)  ... yet two 
GETs typically get different HTTP answers.

Dan


(*) tiptoing past philosophers of language here
Received on Thursday, 14 June 2007 11:17:36 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 1 March 2016 07:41:57 UTC