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Re: Subjects as Literals

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 8 Jul 2010 10:52:57 -0500
Cc: Toby Inkster <tai@g5n.co.uk>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
Message-Id: <19774366-555D-427F-B982-EC50B592ADCE@ihmc.us>
To: nathan@webr3.org

On Jul 6, 2010, at 4:02 PM, Nathan wrote:

> Pat Hayes wrote:
>> However, before I lose any more of my SW friends, let me say at  
>> once that I am NOT arguing for this change to RDF.
> so after hundreds of emails, I have to ask - what (the hell) defines  
> RDF?

Well, the current specs do. And they include a lot more than the  
semantics. In particular, they include syntactic restrictions on what  
can be in what part of a triple, like no literals in the subject  
position. When I say that the RDF semantics works fine for a more  
general version, what I mean is only to reassure folk who know that it  
would be only an editorial matter to change the specs to allow more  
general forms for triples, but who worry (as many folk do) that such a  
change might break something basic in the RDF semantics, which is  
known to be a deep, subtle complicated thingie - to reassure them that  
this will not break the semantics, in fact. Of course, the 'rdf  
semantics' document would need some revision, since it gives for  
inference rules for RDFS which presume that the syntactic restrictions  
are in place, things like that. But these changes would actually  
simplify the way the document is written compared to its present form.

> I've read that 'The RDF Semantics as stated works fine with triples  
> which have any kind of syntactic node in any position in any  
> combination.'
> Do the 'RDF Semantics' define RDF? or do the serializations?

The specs do, which include the RDF graph model as well as the RDF/XML  
serialization, both normative.

> simply - does RDF support literal subjects or not

Right now, it does not.

> - I've read the aforementioned sentence to read 'RDF Semantics  
> support literal subjects' or should I be reading 'RDF Semantics  
> could support literal subjects' or 'does support literal subjects' or?

Could support (with some work, but not too much) is closest to the  
mark. See above.


> Just seeking a definitive bit of clarity on 1: what defines RDF, 2:  
> what is *currently* supported in that definition.
> Preferably a serialization unspecific answer :)
> Best & TIA,
> Nathan

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Received on Thursday, 8 July 2010 15:54:09 UTC

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