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RDF "data model" (was comments on syntax draft)

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Thu, 03 Jan 2002 11:04:37 +0000
Message-Id: <5.1.0.14.2.20020103103830.03962ec0@joy.songbird.com>
To: Dave Beckett <dave.beckett@bristol.ac.uk>
Cc: w3c-rdfcore-wg@w3.org
At 02:33 PM 12/14/01 +0000, Dave Beckett wrote:
>   (Dan)
>   "The RDF Model Theory ([RDF-MODEL]) is a graph consisting of nodes "
>
>   ...the Model Theory itself isn't a graph; it's a theory. So we kind of
>   want to say 'the RDF model is a', except we don't seem to use the word
>   'model' that way anymore. Same goes for 'the RDF data model', I think.
>
>   "The RDF Model Theory" [RDF-MODEL] defines RDF as a graph..." perhaps?

I was thinking, just overnight, that we seem to have kind of backed 
ourselves into a bit of a corner over this "data model" idea, and the fact 
that "model" has a special meaning for logicians.  I think that the 
abstract "data model" is a key backbone of RDF, yet we haven't really 
defined a convenient way to talk about it.

I think the "data model" is central in the sense that (a) syntax can be 
defined as a lexicalization of the data model, and (b) semantics can be 
defined using the "data model" as it's input language for which denotations 
are defined.

I personally would be happy to talk about an "RDF data model", and keep in 
mind that this uses the term "model" quite differently from its use in 
"model theory" (and state this explicitly somewhere), but I also see that 
might be felt to be confusing.  Do we have any other adequately descriptive 
candidates for what to call this?

Anyway, the main point of my overnight concerns was that, while we 
currently have syntax and semantics documents as work in progress, there 
doesn't really seem to be an accessible yet definitive starting point for 
non-logicians that introduces the "data model" independently of any 
particular serialization syntax. [** see below]  (In my work on CC/PP, it 
was grokking the underlying graph model that allowed me to really come to 
terms with what RDF was providing, so I do think this is an important issue.)

Meanwhile, for the syntax document, I'll offer some words:

[[[
RDF is an information representation format that is based on a graph data 
model.  The RDF Model Theory [xxx] gives a formal definition and model 
theoretic semantics for this graph model;  this document defines how the 
graph model can be represented and serialized using XML [xxx].
]]]

[**]
Maybe the "primer" is the right place for the data model to be 
introduced.  My concern with this is that a document titled "primer" is not 
sufficiently definitive.  But I can see that this could work if the primer, 
syntax and semantics were carefully integrated.

Maybe a common introductory paragraph in each of the three documents, 
expanding on text something like that suggested above, would provide the 
needed level of integration and cross-referencing.  I'd be prepared to take 
a shot at drafting this is it's felt to be a useful strategy.

#g



------------------------------------------------------------
Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
<Graham.Klyne@MIMEsweeper.com>
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Received on Thursday, 3 January 2002 08:18:23 EST

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