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RE: The Semantic Web: An Introduction

From: dehora <dehora@eircom.net>
Date: Mon, 17 Sep 2001 14:03:37 +0100
To: "'Sean B. Palmer'" <sean@mysterylights.com>, <www-rdf-interest@w3.org>
Message-ID: <000f01c13f79$2d3befe0$01000001@MITCHUM>
Hi Sean,

Nice to see RDF an article chock full with examples. One nit.

The section "Pedantic Web" discusses confusion between name and entity
using (presumably) the Dublin Core element 'creator'. That element isn't
a good example; 'creator' does allow one to assume that the string value
represents the creating entity. Thus the value of the creator element is
understood to name an authoring entity, not be the authoring entity.
From <http://dublincore.org/documents/dces/> :

"Element:    Creator
Name:        Creator
Identifier:  Creator
Definition:  An entity primarily responsible for making the 
             content of the resource.
Comment:     Examples of a Creator include a person, an organisation,
             or a service. Typically, the name of a Creator should 
             be used to indicate the entity."


Clearly in RDF processing, literals are opaque to RDF (i.e. if a literal
looks like a URI or more RDF, it is treated as a literal, not as a URI
or more RDF). However an application using RDF triples and able to
properly manipulate Dublin Core in your example would be entitled to
draw the inference that the literal names an entity.

You are probably correct about "what the author really means"; but only
as a term rewriting/mapping from Dublin Core to foaf, not as a more
proper data model. A more accurate example would be to show how an RDF
based application could use its knowledge of 'creator' to expand it and
generate a foaf statement, or discuss how machines can use their
knowledge of predicates to make inferences and rewrite terms (and
possibly automagically generate and publish the RDFS to allow other
applications to perform the binding, which is very interesting stuff). 

I believe this confusion (I've seen this example more than once) about
Dublin Core 'creator' in RDF, results from the RDF Model and Syntax use
of a predicate that isn't from the Dublin Core called "creator" in
section 2 and a few people asking the obvious 'is the string meant to be
the author?'. RDF doesn't restrict an RDF based application from
interpreting the literal as it sees fit (RDF doesn't prescribe a
processing model). The only restriction on a literal value in RDF is
that it must not be treated as further RDF at the stage where RDF is
marshalled/demarshalled. What an application does with the consequent
triples is its own business and will largely depend on what it knows
about predicates like 'creator'. Irregardless, more should be done here,
to allow the RDF community to distinguish between an RDF literal (about
which little can be said) and the value of a well known property (about
which quite a lot might be said).

regards,
Bill de hÓra

> -----Original Message-----
> From: www-rdf-interest-request@w3.org 
> [mailto:www-rdf-interest-request@w3.org] On Behalf Of Sean B. Palmer
> Sent: 17 September 2001 01:08
> To: www-rdf-interest@w3.org
> Subject: The Semantic Web: An Introduction
> 
> 
> This is a new article, available from:-
> 
>      http://infomesh.net/2001/swintro/
>      - The Semantic Web: An Introduction
Received on Monday, 17 September 2001 09:05:11 GMT

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