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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.


Clarification:
==============
Jeremy:
> > 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.
Jonathan:
> 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
implementations.



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}
[..snip..]
> 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.

Jeremy
Received on Wednesday, 6 March 2002 04:48:03 GMT

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