W3C home > Mailing lists > Public > www-webont-wg@w3.org > March 2002

RE: LANG, SEM: Re: more on a same-syntax extension from RDF(S) to OWL

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Wed, 6 Mar 2002 09:47:59 -0000
To: <www-webont-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDGEDJCDAA.jjc@hplb.hpl.hp.com>
A small clarification,  and then a more detailed reply.

> > What I have seen so far is the desire to state logical entailments.
> >
> > This is quite addressable outside RDF rather than inside the graph.
> > The N3 version could be modelled in RDF as a load of triples, with N3
> > contexts roughly corresponding to bags of reified triples in RDF.
> Yuck!

Oh yes I share this sentiment.

What I was trying to say, but didn't, was that the bags of reifications is a
possible (but unattractive) approach within RDF.
But outside RDF it is also quite possible to state entailments.

More detail

For example, we can have separate files, some of consequences, some of
conclustions, and then say that files A, B, and C entail files D, E and F.

This can be made formal quite easily.
My belief is that that is sufficient for the only use cases I am aware of
that is in charter for this group. Those use cases are to have clear
discussions within the group and for the stating of test cases for

Entailment & Logic

> Jeremy Carroll wrote:
> > What are the use cases for this ability?
> Basically anywhere you see (in N3) { ... } a context is defined
> in which the
> contents are not necessarily asserted.
> Perhaps the simplest use of this is an IF THEN statement or an OR
> statement
> IF {sky color blue} THEN {trees color green}
> A simple way to write down a simple formula is the use case.

My problem with this is whether the examples are in scope.

I am in this group to help provide a language to specify ontologies for data
and information on the web.

N3 and the examples appear to be trying the rather more ambitious task of
having a web language for writing complex logical expressions. A worthwhile
task, but not my understanding of our task.

I believe that we will need to talk about logical entailment. (In order for
us to discuss and specify the meaning of OWL).

I do not believe that we will need logical entailment in our language.

Received on Wednesday, 6 March 2002 04:48:03 UTC

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