Relevancy of RDF model theory to the Web [was: Re: XML Schema draft ...]

On 29 Sep 2007, at 01:13, Pat Hayes wrote:
> If we temporarily ignore http-Range-14, then there is no connection  
> at all between what RDF means by "denote" and what all other W3C or  
> IETF specs mean by "identify".

Let's be accurate, Pat. There is no connection at all between what  
*rdf-mt* means by “denote”, and what all other W3C or IETF specs --  
including other parts of RDF -- mean by “denote”, “identify”,  
“indicate”, and “mean”.

The border between the Web and that weird parallel URI universe isn't  
between RDF and the rest of W3C/IETF. It's between rdf-mt and the  
rest of the world.

There are many examples throughout the various RDF specs that make  
the intention quite clear: RDF statements about <http:// 
www.example.org/index.html> are intended to be statements about that  
which is identified (in the RFC sense) by that URI -- the web page.

> As far as RDF semantics is concerned, URIs are just blank names  
> with no associated structure or meaning.

I assume by “RDF semantics” you mean the rdf-mt document. Sure, rdf- 
mt takes the syntax of URIs from RFC 2396 but ditches the semantics.  
This is one of the gaping holes left by the WG.

I do understand why the was made -- a coherent account of reference  
on the Web was perhaps impossible prior to httpRange-14. But that  
account is now possible, and the hole can -- and ought to -- be  
filled, by the semantic extension alluded to in [1]. Don't give me  
any of that “It's that way by design” crap.

>> There is a school of thought that wants to see URI-space as a  
>> blank slate for the purposes of RDF, completely disconnected from  
>> the role of URIs on the Web. Personally, I have trouble seeing the  
>> advantage of this view. If you want to operate in a universe  
>> parallel to the Web, then why use URIs in the first place? Why not  
>> simply use KIF or CL?
>
> There are reasons, connected with the global uniqueness of URIs.  
> But I tend to agree about CL (which can use URIs as names, if one  
> wishes to.)
>
>> (Although, in defense of the ³parallel universe² school, this view  
>> is legitimized by a passage in rdf-mt [2], which, it appears,  
>> directly contradicts rdf-concepts [1].)
>
> I don't think it does. Where do you see the contradiction arising?

If you take the position that “denote” in rdf-mt means something  
different from “identify” in rdf-concepts or rdf-primer, then there  
is of course no contradiction. I call that the “RDF model theory is  
irrelevant to the Web” position.

I'd much rather like to know what an extension of the RDF semantics  
that takes the Web into account would look like.

Richard

[1] http://www.w3.org/TR/rdf-mt/#urisandlit


>
> Pat
>
>>
>>>> No, you are wrong.
>>>> RFC 3986 says that the "nature" of <doc#term> is
>>>> determined by the media type of <doc>, governed by the RFC that has
>>>> registered that media type. The registration for HTML says that
>>>> fragments identify parts of the HTML document;
>>>
>>> Yes, I gathered this from Dan's follow-up response about the HTML  
>>> RFC
>>> being the source of the 'problem'.  Still, the ambiguity you are
>>> speaking about is between two completely orthogonal mechanisms for
>>> reference ("identification" versus denotation).
>>>
>>> Frankly (and this has been my perpetual theme), if there is serious
>>> concern about ambiguity, then a language well-equipped to handle
>>> ambiguity should be used.
>>
>> I do not believe that such a language can resolve the ambiguity.
>>
>> Quoting RFC 3986:
>>
>> ³If the primary resource has multiple representations, as is often  
>> the case for resources whose representation is selected based on  
>> attributes of the retrieval request (a.k.a., content negotiation),  
>> then whatever is identified by the fragment should be consistent  
>> across all of those representations.²
>>
>> Combining a text/html representation with an application/rdf+xml  
>> representation makes it hard to achieve this consistency, unless  
>> additional webarch trickery is used (303).
>>
>> The ambiguity arises on the webarch level, and can only be  
>> resolved there.
>>
>> Yours,
>> Richard
>>
>> [1] http://www.w3.org/TR/rdf-concepts/#section-fragID
>> [2] http://www.w3.org/TR/rdf-mt/#urisandlit
>>
>>> A vacuous notion of "identification" is
>>> simply not sufficient.
>>>
>>>> the registration for
>>>> RDF says that fragments can identify things outside of the  
>>>> document.
>>>> Thus the ambiguity.
>>>
>>> See above.
>>>
>>>  -- Chimezie
>
>
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Received on Saturday, 29 September 2007 16:03:11 UTC