W3C home > Mailing lists > Public > www-rdf-logic@w3.org > January 2005

Re: RDF as a syntax for OWL (was Re: same-syntax extensions to RDF)

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Thu, 6 Jan 2005 00:27:47 +0900
Message-Id: <5AB8D794-5F2E-11D9-AA78-000D93C1F7A6@isr.umd.edu>
To: www-rdf-logic@w3.org

On Jan 5, 2005, at 11:29 PM, jos.deroo@agfa.com wrote:

> Yes, but we do OWL/RDF/XML<->RDF/N3 automatically (using
> Jena2 or Cwm) and then just *add* explicit theories such as
> e.g. the ones in http://eulersharp.sourceforge.net/#theories

Would you be comfortable using such a theory as a specification for the 
semantics of OWL? (Pace minor bugs, natch.)

> Indeed, the latter is still a matter of "selecting by human".
> At this moment RDF/N3<->TSTP transcription is semiautomatic
> and is why I will have to come back later when I have more
> running code to sharply illustrate what I found feasable :)

Jos, I have a way way easier challenge: do the negation normal form 

Specification: Given an input graph, produce an output graph such that 
all negations appear only on class names in a class expression.

Actually, let's make it even easier! Only for ALC

I'll even give the rules:
	I'll use ~ for not (complementOf)
		& for conjunction (intersectionOf)
		v for disjunction (unionOf)
		some for existential quantification (someValuesFrom)
		all for universal quantification (allValuesFrom)
	I'll use fairly normal infixy syntax. I'll happily convert to 
something else.
	For (compound) class expressions C and D
		nnf(~~C)) => nnf(C)
		nnf(~(C & D)) => nnf(~C) v nnf(~D)
		nnf(~(C v D)) => nnf(~C) & nnf(~D)
		nnf(~some(P, C)) => all(P, nnf(C))
		nnf(~all(P, C)) => some(P, nnf(C))

	Base case: for atomic class name C
		nnf(C) => C
		nnf(~C) => ~C

That's almost the prolog program :)

I'll accept the binary restriction on & and v.

To make it easier, I'll allow for the class expressions to be isolated 
(i.e., not part of an axiom), if that helps.

I believe this exercise will be illuminating to anyone who tries it.

Actually, just trying stating the rules using RDF triples in your 
favorite syntax.

Bijan Parsia.
Received on Wednesday, 5 January 2005 15:27:44 UTC

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