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Re: Semantic Web + Logic

From: Wolfram Conen <conen@gmx.de>
Date: Fri, 05 Oct 2001 10:13:42 +0200
Message-ID: <3BBD6BB6.1B8A74CF@gmx.de>
To: Fernanda Hembecker <fernanda@ppgia.pucpr.br>
CC: www-rdf-interest@w3.org
Fernanda Hembecker wrote:
> 
>     I am from Brazil and I am studing Semantic Web, but I am really
> interested in to know more about Logic and Semanti Web applications. Is
> there anything already done in this area? What kinds of logic can be
> manipulated in Semantic Web? I am trying to create a practical example,
> where I could apply a kind of an inheritance reasoner (to make
> inferences about the content of the RDF pages), but I didn't find a good
> one.
> 
>     I really apreciate your help.
> 
>     Best regards,
>         Fernanda.
> 
>

Fernanda,

a lot could be said as an answer to your request. Maybe a better place
for this kind of request would be the rdf-logic-list. There is a lot of
stuff going on (related to DAML+OIL mostly) related to Semantic Web +
Logic.

However, if you are interested in doing some practical, working example
that still rests on the (syntactic and semantic*) fundaments of RDFS,
you may want to play with our RDF Schema Explorer. On first sight, this
baby looks to be very much "bare bones", but underneath, its really easy
and fun to experiment, even work with (IMHO). You find it at
http://wonkituck.wi-inf.uni-essen.de/rdfs. 
You can feed RDFS into it (including horn clauses (Prolog to be precise)
to define the semantics of new properties), validate it against RDFS
constraints (like domain/range), extend such constraints, make queries
(with Prolog or self-defined properties) etc. To understand what's going
on inside, you may want to read up the following two papers:

A logical interpretation of RDF 
http://nestroy.wi-inf.uni-essen.de/rdf/logical_interpretation/
(still under Review for the Semantic Web Section of the ETAIJ
(www.etaij.org))
-- this paper discusses a horn clause formalization of RDFS

Utilizing Host Formalisms to Extend RDF Semantics
http://nestroy.wi-inf.uni-essen.de/~conen/conen/paper/swws/paper24.pdf
(Published in the proceedings of the SWWS/Stanford
(www.semanticweb.org/swws))
-- this paper gives an account of a detailed example that demonstrates
how the schema explorer can be used to extend the (rather meager)
semantics of RDFS/RDF.

If you have further questions, do not hesitate to contact me or Reinhold
(Reinhold.Klapsing@uni-essen.de).

Viele Gruesse,
	Wolfram
	Xonar GmbH

(*some people may not share this view, now, with the model theory under
development. For example, one remarkable difference between the RDFS
closure in the MT document and our "interpretation" of the semantics
with (almost) horn clauses is that to compute the closure in the Schema
Explorer takes you one second (select "All Triples" from the menue)
while "operationally" interpreting the MT document may take a while (and
may lead to a very similar result) ;)  (to be serious: once the
discussion of the RDF/RDFS semantics has come to an preliminary end, it
should be possible to adapt the Schema Explorer to those changes rapidly
(if Herbrand interpretation are ok for you), so, what you learn from
experimenting with it will hopefully not be a futile effort).
Received on Friday, 5 October 2001 04:10:18 GMT

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