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Re: declaredAs

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Fri, 10 Aug 2007 21:19:06 -0400
Message-Id: <A6559D36-CF36-4627-A5C3-EED96BEA2FEE@gmail.com>
Cc: "Pat Hayes" <phayes@ihmc.us>, "Bijan Parsia" <bparsia@cs.man.ac.uk>, "Owl Dev" <public-owl-dev@w3.org>
To: John McClure <jmcclure@hypergrove.com>

I wondered about the same thing but concluded that it was just dumb.  
I'd be happy to find I was wrong, but haven't heard anything yet to  
support the alternative. I virtually never[*] use rdf:ID because it  
has silly constraints on the form of identifiers. Moreover, because  
of this, it would be impossible to use it to make declarations of  
many possible names in the language. For example,

From: http://www.w3.org/TR/rdf-syntax-grammar/#section-Identifiers

"The rdf:ID values are transformed into RDF URI references by  
appending the attribute value to the result of appending "#" to the  
in-scope base URI which is defined in Section 5.3 Resolving URIs"

Given this, there is no way to use rdf:ID to talk about a URI which  
doesn't contain a "#". If the intent was to have rdf:ID serve a  
distinct purpose from rdf:about that was important, then a major  
mistake was made, as there is no way to use it to talk about many URIs.


[*] I have on occasion used rdf:ID on the predicate of a triple as a  
concise way of reifying a triple. See http://www.w3.org/TR/rdf-syntax- 

On Aug 10, 2007, at 6:16 PM, John McClure wrote:

> Interesting. If there is no difference in the semantics, then why  
> was rdf:ID
> created in the first place?Why is it necessary to have this  
> declaredAs if there
> is no difference, whose function appears to be to differentiate?  
> Seems pretty
> *darn* (smile) clear to me that rdf:ID functionally duplicates XML  
> ID and is
> hence a declaration because it'd be dumb to have multiple  
> definitions for
> something in the same *context*, a concept enforced by XML ID.   
> Anyway what do
> you think a model would look like that contains Statement, Assertion &
> Declaration classes -- surely you're not saying that such a model  
> would be
> senseless to consider or build!
> Thanks
>> -----Original Message-----
>> From: Pat Hayes [mailto:phayes@ihmc.us]
>> Sent: Friday, August 10, 2007 1:58 PM
>> To: John McClure
>> Cc: Bijan Parsia; Owl Dev
>> Subject: RE: declaredAs
>>>> But rdf:ID doesn't get you *any sort of
>>>> declaration*. It's *just a funny way of making an assertion*.
>>> Nope, I don't agree -- I don't see this in the specs anywhere.
>> Well, the RDF specs say explicitly that RDF consists entirely of
>> assertions, they give a normative semantics which defines the
>> assertions, and they do not mention declarations anywhere. Seems
>> pretty damn clear to me.
>> Pat Hayes
>> --
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Received on Saturday, 11 August 2007 01:19:20 UTC

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