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Len, I agree with what you say below.
To be clear, RDF is not _itself_ an ontology language.
But one can develop an ontology language e.g. DAML or
OWL which is based upon RDF, i.e. is written in RDF
syntax (triples) and at the same time XML (as a dialect
At the same time, via XML datatypes, one can speak about
(e.g. make assertions about, or classifications of)
pieces of structured data in OWL.
In RDF you can assign a type (i.e. place into a
classification) with an "rdf:type" arc e.g.
<http://example.org/foo> rdf:type owl:Class .
now assuming that you have an XML Schema type you might
integrate this with OWL as such:
my:date-format rdf:type owl:DatatypeProperty .
so the idea that a fragment of XML conforms to a certain
XML Schema _type_ is the same as saying that such a
fragment belongs to a corresponding OWL _Class_.
So in summary, you might assign free-form
RDF 'individuals' to classes, and you might also assign
fragments of markup to classes, both using OWL (which is
the successor to DAML).
Both RDF and XML approaches to
classifications/ontologies need to coexist on the
> Which is why we were going to markup even before the web: to seed the
> classification of the published information, to build "local contexts".
> Again, markup is not about identification; it is about classification.
> The notion was that free text data using RTF-like systems organized and
> labeled for presentation, not querying, or reuse. The horror on the
> SGMLers faces when given HTML was not that it would be an unworkable
> system; we knew it would go as all gencoding does, like a grassfire.
> The horror was that it returned us to and amplified the bad old days
> of data not being reusable or easily classifiable.
> The idea for content-modeled SGML was that preclassifying the information using
> intelligence (authors) would help. HTML set everything back about two
> decades (a success for publishers but a disaster for everything else).
> RDF is a better ontology language but once again, one gets that HTML
> effect of predetermined definitions over syntax at the level of
> the classifying terminology. There is a definite deja vu in the semantic web.
> This doesn't mean RDF doesn't work or isn't a more precise means of
> classification. It is.
> What would be the effect (theoretically) of ceasing to use HTML for
> any records of authority (assertions for data mining candidates)
> and using XML without RDF? One lives without asserted relationships
> for one. Ok, so Topic Maps are added. What then is the role
> of RDF?
> I ask because although the answers are somewhat obvious, it is also
> obvious that RDFing any information published is too much overhead
> and the ROI has to be good before people will do it. On the other
> hand, the use of XML DTDs and schemas is already well accepted and
> it may be preferable to focus development of engines that mine based
> on these.
> One point of the article referenced originally was that Google could
> live large using the same web we have now and not have to insist on
> a stratified web. Of course, some potential profits based on hoarding
> the ontologies disappears, but that is an information ecosystem
> catastrophe in the making anyway.