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RE: Is n3 a rules language or a logic language?

From: Wagner, G.R. <G.R.Wagner@tm.tue.nl>
Date: Fri, 13 Dec 2002 01:24:01 +0100
Message-ID: <AA2E843B3FC96349BF60350202650BE925739E@tmex1.tm.tue.nl>
To: "'pat hayes'" <phayes@ai.uwf.edu>, "Wagner, G.R." <G.R.Wagner@tm.tue.nl>
Cc: Sandro Hawke <sandro@w3.org>, www-rdf-rules@w3.org, timbl@w3.org, pfps@research.bell-labs.com

> >and KR is not a branch of classical/mathematical logic but rather
> >the other way around.
> 
> My goodness, ... I absolutely do not accept your premis here.

I know :-)

> >In real world domains, and in natural language,
> >we use the term "rule" for denoting many different things with very
> >different semantics.
> 
> I take it then that 'rule' in Rule ML can have no single semantics, 
> and that (very much in the XML spirit) , RuleML is not intended to 
> convey a uniform semantic framework, but instead to be all things to 
> all men? 

Having different semantics for different types of things does not
mean to have "all things to all men"! We need different semantics
for different types of derivation rules, and still different
semantics for reaction rules and for deontic assignment rules,
in the same sense as there are different semantics for different
types of implication (such as material implication, intuitionistic
implication and relevant implication).
 
> Yes, the discussion on this thread has been about rules in two 
> senses: inference rule as in logic, and 'rule' as in logic 
> programming, where it refers to a Horn clause.

Rules in normal (and even less in extended) logic programs are
not Horn clauses!
 
> I note that all the 
> examples you cite are systems which are considered to be a kind of 
> programming language, and those, of course, typically do not have a 
> normal assertional semantics. 
 
Logic "programming" languages have never been very successful as 
programming languages, but rather as specification and KR languages.
Extended/intuitionistc/fuzzy/etc. logic programs do have an 
"assertional" (model-theoretic) semantics. But unlike that of
RDF and OWL, also because they have additional connectives,
these semantics are non-classical.

-Gerd

---------------------------------------
Gerd Wagner  
http://tmitwww.tm.tue.nl/staff/gwagner/
Dep. Information & Technology 
Eindhoven University of Technology  
Email: G.Wagner@tm.tue.nl 
Phone: (+31 40) 247 26 17  
Fax: (+31 40) 247 26 12
Received on Thursday, 12 December 2002 19:24:22 GMT

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