W3C home > Mailing lists > Public > www-rdf-logic@w3.org > July 2003

RE: Defining "flavors" of subClassOf in OWL ?

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Tue, 15 Jul 2003 16:52:17 +0200
To: "Www-Rdf-Logic@W3.Org" <www-rdf-logic@w3.org>
Message-ID: <GOEIKOOAMJONEFCANOKCMEDICCAA.bernard.vatant@mondeca.com>


Hi Dan

Thanks for your answer. Some precisions ahead.

> I'm not sure exactly what you mean by "OWL validator".

Well, certainly I'm not sure myself, that's why I've been trusting the
quoted tools which present themselves under such a name. This is the same
"black box" approach I use with an XML editor to validate a file against a
DTD/Schema. "Those guys know best" is certainly a naive approach, but it's
very likely that people as naive as I am (or even possibly more naive) will
do the same.

> >  is it that subtyping "subClassOf" is altogether invalid in OWL ...?
>
> only in OWL DL (and hence in OWL Lite).

OK, got it. This is because "subClassOf" is neither a data-valued property
nor an individual-valued property, unless your consider classes as
individuals, which is only allowed in OWL Full. Right?

> If you're trying to get a lot of "yes, that document is squeaky
> clean" checking, you might want to stay inside OWL DL;
> you'll have to find a work-around for expressing what you
> want to express in that case, though.

Well, unfortunately, I've considered that from all sorts of ways I could
imagine, and could not find any solution so far - although I can imagine a
lot :) I have to represent classes as individual topics at some point. And
considering an individual topic otherwise than an (OWL) individual is
something clearly difficult to "work-around"...

This of course could bring water to the mill of those who pretend that if
Topic Maps have no proper semantic model so far, that's because it's
impossible to set one, at least using DL. Not being able to model TM in OWL
DL is not necessarily bad news, though, if everyone is aware that TM can
live on this loose but expressive ground defined by OWL Full ...


Bernard Vatant
Senior Consultant
Knowledge Engineering
Mondeca - www.mondeca.com
bernard.vatant@mondeca.com


> -----Message d'origine-----
> De : Dan Connolly [mailto:connolly@w3.org]
> Envoyé : jeudi 10 juillet 2003 23:40
> À : Bernard Vatant
> Cc : Www-Rdf-Logic@W3.Org; Frédéric Delahaye
> Objet : Re: Defining "flavors" of subClassOf in OWL ?
>
>
> On Thu, 2003-07-10 at 11:19, Bernard Vatant wrote:
> > In Mondeca ITM internal management of classes, we have a generic
> > functionality somehow equivalent to the distinction between
> "abstract" and
> > "concrete" classes in Protégé. However, the distinction is not made by
> > typing the classes themselves, but by typing the class-subClass
> > relationship (aka Topic Map association). This means we have
> two "flavors"
> > of subclassing, supporting different technical treatments.
> >
> > Trying to represent this in OWL, I defined two properties like
> >
> > p1 rdfs:subPropertyOf rdfs:subClassOf
> > p2 rdfs:subPropertyOf rdfs:subClassOf
> >
> > Now if I have three classes X, Y, Z such as (X p1 Y) and (Y p2 Z)
> >
> > I expect from the semantics of subPropertyOf that an OWL
> validator would
> > infer:
> > (X subClassOf Y) (Y subClassOf Z) (X subClassOf Z)
>
> That conclusion does follow in OWL full, since...
>
> "T-interpretations must meet several other conditions, as detailed in
> the RDF semantics."
>  -- http://www.w3.org/TR/owl-semantics/rdfs.html#5.2
>
> <x,y> is in IEXT(I(rdfs:subPropertyOf)) if and only if x and y are in IP
> and IEXT(x) is a subset of IEXT(y)
>
> -- http://www.w3.org/TR/2003/WD-rdf-mt-20030123/
>
>
> I'm not sure exactly what you mean by "OWL validator".
>
>
> > Meaning if an ObjectProperty q has been declared e.g. of range
> Z, it should
> > be validated if used with values in X.
>
> I think your intuitions are in the right direction, but again,
> I'm not sure what "validated" means, exactly.
>
>
> > Not quite sure about it, I've tested precisely that situation
> on an example
> > [1], and my two favourite OWL on-line validators seem to differ on the
> > validation results.
> >
> > http://phoebus.cs.man.ac.uk:9999/OWL/Validator seems happy with it.
>
> That one just tells you whether a document is in one of the dialects;
> every RDF document is an OWL Full document, so you're not getting
> much information there. That tool doesn't find inconsistencies,
> for example.
>
> > http://owl.bbn.com/validator/ is not, and sends back a bunch of "range
> > mismatch" error.
>
> That employs a number of heuristics to find common problems.
> It seems to be confused in this case.
>
> > Is this a bug in the validator, or is it a borderline example,
>
> Playing with the built-in vocabulary is in some sense borderline,
> though it's perfectly well specified in OWL full.
>
> >  or is it
> > that subtyping "subClassOf" is altogether invalid in OWL,
>
> only in OWL DL (and hence in OWL Lite).
>
> >  or what?
> >
> > A bottom line question is to know if that could be considered a
> > recommended/neutral/bad practice.
>
> It seems like a pretty natural way to model your situation,
> and the conclusions you mention do follow...
>
> If you're trying to get a lot of "yes, that document is squeaky
> clean" checking, you might want to stay inside OWL DL;
> you'll have to find a work-around for expressing what you
> want to express in that case, though.
>
> See section 3.1.3. Design for Use
> http://www.w3.org/TR/owl-guide/#DesignForUse
> for a discussion of some of the trade-offs.
>
> > Thanks for your help
> >
> > Bernard Vatant
> > Senior Consultant
> > Knowledge Engineering
> > Mondeca - www.mondeca.com
> > bernard.vatant@mondeca.com
> >
> > [1]
> >
http://www.daml.org/cgi-bin/hyperdaml?http://www.mondeca.com/owl/itmex.rdf

--
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Tuesday, 15 July 2003 10:52:34 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:52:47 GMT