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Re: Non-monotonic

From: Sean Mehan <sean@smo.uhi.ac.uk>
Date: Fri, 14 Nov 2003 15:18:04 +0000
Cc: minsu@etri.re.kr, www-rdf-rules@w3.org, www-rdf-interest@w3.org
To: adrianw@snet.net
Message-Id: <BE55921A-16B5-11D8-869F-000A956F1E32@smo.uhi.ac.uk>
Err, unless it is far too late and I am missing the snake right in 
front of my nose, Adrian is arguing for a nonmonotonic reasoning, which 
is what Minsu wants.

Nonmonotonic reasoning is the ability to mkae assertions about the 
domain (push new facts on the stack) which may later be modified or 
retracted (pop the facts).

The  question I have is how often do we need open world? In other 
words, how often would a closed world assumption supporting logic be 
good enough?

Regards,
Sean

On Thursday, November 13, 2003, at 02:56 PM, Adrian Walker wrote:

> Minsu --
>
> You wrote...
>
> Web ontologies *should* independently evolve.
> In this regard, I think rule languages and processors for the semantic
> web
> should address problems of reasoning in the open knowledge space,
> which is non-monotonic in its nature.
>
>
> I often see statements of this kind from the RDF and semantic web 
> folks.
>
> In the real world, if I tell you that  
>
>            can_fly(X) if bird(X) & not penguin(X)
>            
>            bird(Fred).
>
> you will presumably conclude that Fred can fly.  If I later add 
> penguin(Fred), you will no longer conclude that Fred can fly.
>
> This may sound naive, but can you argue for me please why the above 
> should be ruled out on the Semantic Web ?  Seems like you are throwing 
> out the bird with the bathwater (:-)
>
> Thanks in advance,   -- Adrian
>
> -- 
>
>               INTERNET BUSINESS LOGIC
>  Business Rules in English + Your Oracle Databases
>               www.reengineeringllc.com
>
> Dr. Adrian Walker
> Reengineering LLC
> PO Box 1412
> Bristol, CT 06011-1412, USA
>
> Phone: 860 583 9677
> Fax:   860 314 1029
> Cell:  860 830 2085
>
>
>
> [Dan Brickley wrote,]
>
>
> * Minsu Jang <minsu@etri.re.kr> [2003-11-08 14:26+0900]
>
>
> - OWLer: an OWL inference system. It uses JTP for inferencing.
> - ezOWL: a Protege plugin for visual editing of OWL documents.
> - MOA: a merging tool for merging multiple OWL ongologies.
> - Buchingae: a web-friendly rule language. not XML-based.
> - LogicML: a rule markup language, which is a slight extension of
> RuleML's hornlog.
>
>
> ...same question as above! Where/when can we find out more?
>
>
>
>
> Most of these are not documented well yet, but ezOWL is
> published under plugins directory of Protege.
> You can find more about the plugin at http://iweb.etri.re.kr/ezowl/.
>
>
>
> I notice in
>
>
> http://machine-knows.etri.re.kr/bossam/download/download.html that
>
>
> the engine isn't public yet. Do you have a sense for when it will be
> available, or expectations about likely license terms? (opensource
>
>
> would
>
>
> be great...)
>
>
>
> The engine will be available with the similar licensing terms to that 
> of
> Jess.
>
>
>
> A technical question (for everyone, really):
> The Web Ontology WG spent a lot of time and energy
> on the delicate balance between OWL DL and OWL Full. Do you have any
> findings from your implementation work that would help us estimate the
>
>
>
>
>
> impact of this aspect of OWL on any future Rules standardisation? Is
> it feasible to keep both traditions/approaches/communities happy
>
>
> within
>
>
> a single "OWL-compatible" rules language?
>
>
>
>
> I don't have good technical background on computational logics or
> mechanical theorem proving, so what I'm going to say could be
> a disaster for this list. ;-) Even if so, please don't hrurry for
> escaping,
> but be generous enough to provide your invaluable teachings.
>
> Bossam is just a production rule system with some extended knowledge
> representation elements which make the engine suitable for inferencing
> over OWL ontology. When I started to write OWL inferencing rules, I did
> not
> fully understand what makes OWL Full and OWL DL different.
>
> The only thing I knew was that OWL properties, classes and individuals
> are
> pairwise disjoint in OWL DL, but interchangeable in OWL Full.
> This discrimination rule should be reflected in OWL inferencing rules
> for OWL DL.
> For OWL Full, all the facts and rules of RDFS should be added, and OWL
> class
> should be declared to be owl:equivalentClass to rdfs:Class.
>
> What I have found until now is that the expressiveness of rule language
> is
> not very different whether it's for reasoning over OWL Lite, DL or 
> Full.
> The difference lies in the rulebases. When you write a rulebase
> for reasoning over OWL Lite ontology, you will end up with a smaller 
> set
> of rules.
>
> What I have in mind from my implementation experiences is that
> a single rules language is enough for OWL inference.
>
> One thing I'd like to address at this point is that when you start to
> write
> rules for real applications, the situation becomes very complex.
> It's not OWL inferencing, but real knowledge processing. The web is 
> open
> and many web users will want to process knowledge in the open web, 
> which
> will contain many knowledge elements which contradict each other.
> Even if you preset all the ontologies for a reasoning session, the
> situation
> does not become more optimistic, because web ontologies are not
> controlled.
> Web ontologies *should* independently evolve.
> In this regard, I think rule languages and processors for the semantic
> web
> should address problems of reasoning in the open knowledge space,
> which is non-monotonic in its nature.
>
>
>
> BTW http://machine-knows.etri.re.kr/bossam/docs/owlinference.html
>
>
> doesn't
>
>
> explicitly mention OWL DL vs Full or Lite. Which flavour(s) are you
> targetting?
>
>
>
> Um, I did not target any one species (:-\), but the rulebase I'm 
> working
> on is
> targetting OWL Full. And I have a plan to write two more sets of rules
> for
> OWL DL and Lite.
>
> Regards,
> Minsu
>
>
>
>
>
>
> -- 
>
>               INTERNET BUSINESS LOGIC
>  Business Rules in English + Your Oracle Databases
>               www.reengineeringllc.com
>
> Dr. Adrian Walker
> Reengineering LLC
> PO Box 1412
> Bristol, CT 06011-1412, USA
>
> Phone: 860 583 9677
> Fax:   860 314 1029
> Cell:  860 830 2085
>
>
Received on Friday, 14 November 2003 10:54:58 GMT

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