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Re: isDefinedBy and isDescribedBy, Tale of two missing predicates

From: Nathan <nathan@webr3.org>
Date: Fri, 05 Nov 2010 15:29:23 +0000
Message-ID: <4CD422D3.20701@webr3.org>
To: Ian Davis <lists@iandavis.com>
CC: Leigh Dodds <leigh.dodds@talis.com>, Dave Reynolds <dave.e.reynolds@gmail.com>, "public-lod@w3.org" <public-lod@w3.org>
Ian Davis wrote:
> On Fri, Nov 5, 2010 at 1:49 PM, Nathan <nathan@webr3.org> wrote:
>> Any advance?
> I've written on it extensively and linked to two pieced in my recent
> 303 blog post:
> http://iand.posterous.com/2007/11/fragmentation-reprise

   The core of the problem is that hashed URIs are inherently ambiguous.
   Its meaning depends on how you access it, which is nuts. Its as though
   a word has different meanings depending on whether you read it in a
   book or have it read out to you.

No the meaning of any RDF URI Reference is the meaning which you give to 
it by making statements which include it, it's just a logical constant, 
a name.

> http://iand.posterous.com/2007/11/its-ok-to-use-uris-with-fragments-in-rdf

sigh, in to the depths of pedantic serialization specific minor age old 
issues which have never been proven to affect anything really we go:

   ... further away from today's web of documents. For example, when I
   use "http://www.w3.org/TR/webarch/#media-type-fragid" as a URI in my
   RDF, it probably doesn't refer to the thing you think it does. You, as
   a human (if you are), get to see a representation of that section of
   the document when you click on the link, but an RDF-aware agent must
   treat that URI as though rdf/xml had been retrieved.

Can you expand on what that means, because all I'm seeing is if an 
RDF-aware agent did "treat that URI as though rdf/xml had been 
retrieved" then it wouldn't have a description of the thing identified 
by <http://www.w3.org/TR/webarch/#media-type-fragid> == no problem.

   Unfortunately there isn't any RDF there and the Web Architecture
   actually forbids you from serving up both HTML and RDF documents at
   the same URI.

Better clear that up, noticed that it's an age old XHTML-RDFa potential 
issue, so I'll see if we can get it covered in the WG and relay back to 
the TAG to hopefully clear the issue.

AFAIK though, there is nothing stopping you from serving HTML and RDF 
documents at the same URI, in fact that would mean you can't serve up 
RDFa, which clearly is incorrect.

    How can RDF co-exist with other formats on the Web if it ignores
    their semantics?

Either you mean that RDF should be aware of the semantics of every media 
type on the web, or your saying that an RDF Graph should somehow be 
aware of something it's not aware of (it's just statements, names and 
literals) - or your making reference to the Generic processing of 
Fragment IDs in RFC 3023bis issue around rdf:ID.

Quite sure this doesn't affect any other serializations (since they're 
not XML based), so from that standpoint all of this is purely RDF/XML 
specific, and could be fixed / cleared.

Was hoping for something of more substance with some kind of real 
technical effect, not a path in to the depths of minor differences 
between various specifications published over a decade long time line 
tbh, something tangible.


Received on Friday, 5 November 2010 15:30:36 UTC

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