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RE: Semantic languages and rules

From: Charlie Abela <abcharl@keyworld.net>
Date: Tue, 18 Feb 2003 17:16:17 +0100
To: "Daniel Elenius" <danel698@student.liu.se>
Cc: <www-rdf-logic@w3.org>
Message-ID: <OBEOLJNEPKKHAJJIGKDKEEMGCCAA.abcharl@keyworld.net>

Hi

Well from my experience, I found that a parser is useful only to get at the
syntactic structure of a knowledge base (assuming that we are referring to
this as being an ontology of facts). What one requires is an inference
engine. This is most important when using semantic languages since they can
exploit the full potential of such languages. An inference engine will
probably be given a knowledge base of facts which is parsed and from which
new facts can be inferred. Hence such an engine will definitely make use of
a parser internally (an RDF parser if one is speaking about RDF based
languages such as DAML+OIL and DAML-S) and it can also have a query
mechanism. When can find several inference engines for DAML+OIL but none are
really available for DAML-S, since the DAML-S ontologies are nothing more
then DAML+OIL ontologies defining services. Nonetheless if one wants to
exploit DAML-S to the full one has to use/augment such an engine to handle
the DAML-S constructs. One such engine that I used is an FOL reasoner called
JTP (Java Theorem Prover) from Stanford university (even though one ahs to
use a DL based engine since FOL has some drawbacks as regards such semantic
languages).

Regards

Charlie

-------------------------------------------------
Charlie Abela
MSc Research Student,
CSAI Dept., Univ. of Malta,
MSD06. Malta
Web: http://alphatech.mainpage.net
Email: abcharl@keyworld.net

-----Original Message-----
From: Daniel Elenius [mailto:danel698@student.liu.se]
Sent: 18 February 2003 16:56
To: Charlie Abela
Subject: Re: Semantic languages and rules

I want to know these things too. What's the relationsship between
inference engines, query systems, knowledge bases, parsers, etc. and
what is a good setup if I want to use DAML-S files to describe services
and do searches/queries on these descriptions?

regards
daniel


On Tue, 2003-02-18 at 16:28, Charlie Abela wrote:
> Hi all,
>
> I have read the mailing thread RE: Action Items written by Pat Hayes and
> dated 02/12/03 in the US/EU joint-committee archive. It sparked some
> thoughts in my mind about some issues which a newbie like myself might
take
> as forgranted. I am presently doing some research on semantic web
> applications in particular about semantic web services composition. From
> what I have been reading about rules, rule markup, defintion of business
> rules, use of rules for Ws composition, I am now feeling a bit confused
> about all this.
> Consider DAML+OIL, based on DL and capable of expressing knowledge in
> machine interpretable format. With DAML+OIL one can specify a number of
> facts from which inferencing of other facts can be made. So why is it
> necessary for DAML+OIL or OWL (being based on it, even though more
> expressive) to be augmented with rules? Where will these be introduced in
> TBL's semantic web layers?
> Also and this question might be more appropriate in the ws-mailing list:
how
> important is the use of rules in defining ws composition, when one
considers
> the expressivity of languages such as DAML-S.
> Can someone clarify in laymens terminology these issues. Or am I missing
> something?
>
> Regards,
>
> Charlie
>
>
>
>
>
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--
Daniel Elenius <danel698@student.liu.se>



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Received on Tuesday, 18 February 2003 11:13:02 GMT

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