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From: Benjamin Nowack <office@e-senses.de>
Date: Fri, 3 Oct 2003 15:38:12 +0200
To: frozados@fibertel.com.ar
Cc: "RDF-Interest" <www-rdf-interest@w3.org>
Message-ID: <PM-EH.20031003153812.D9A33.2.1D@>

Hi Federico,

thanks so much for posting something that is not about
"the info URI scheme". ;-)

Which technology to use depends on your objectives. You can
use plain RDF to describe arbitrary things (e.g. the mozilla browser
uses RDF internally without any direct relation to the semantic web).

W3C's Metadata Activity and Semantic Web Activity were/are specifying
RDF vocabularies for the Semantic Web. RDF Schema (year 2000 I think)
offers means to model taxonomies and to specify properties some 
class/concept may have. So if you have some RDF instance data that
validate against a specific RDF Schema, software can already do a 
lot of reasoning based on your RDF code (b.t.w. if you are looking 
for an example of applied RDF technology, you may have a look at the
FOAF project at http://www.rdfweb.org/. They are already doing 
amazing things.)
If you need something that is more expressive than RDF Schema, consider 
ontologies. With OWL you can model inverse, symmetric, and transitive
properties, you can define mappings between different 
vocabularies/ontologies, you can specify cardinalities in more detail,
describe classes via boolean combinations of other classes, and a lot 
more. Again, you could have a look at the FOAF spec which is using
OWL constructs to enhance its RDF Schema.

One point to add: Although the Semantic Web Stack (for example at
http://www.w3.org/2003/Talks/0922-rsoc-tbl/slide30-0.html) may give
the impression that OWL is an add-on or extension to RDF Schema, this
is not really the case. OWL classes are subclasses of RDFS classes as
long as you stick to OWL Lite and OWL DL. This means that you cannot
easily reuse RDFS vocabularies within OLW (Lite/DL) ontologies. Or 
the other way round: If you add OWL constructs to your RDF Schema
document, only OWL Full parsers/reasoners will be able to understand
the additional assertions.

hope that helps..

Benjamin Nowack
Am Exerzierplatz 1
DE-97072 Wuerzburg

frozados@fibertel.com.ar (frozados@fibertel.com.ar) schrieb am 02.10.2003:
>Hello. Finally, I will continue para thesis. I have to do an example of
>RDF technology, but i don't see or underestand the usage of OWL and DAML+OIL.
>In which cases i have to use OWL and in which cases i must use pure RDF
>without OWL onthology. 
>I hope anybody can help me, 
>thanks a lot,
Received on Friday, 3 October 2003 09:48:39 UTC

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