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Re: Inferring Class Membership w/o OWL Full?

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Tue, 11 May 2004 21:37:20 +0100
Message-ID: <16545.14720.934293.945455@excalibur.cs.man.ac.uk>
To: Pat Hayes <phayes@ihmc.us>
Cc: Stephen Rhoads <rhoadsnyc@mac.com>, www-rdf-logic@w3.org

On May 7, Pat Hayes writes:
> 
> >For those who didn't follow the debates on the webont mailing list, I
> >should perhaps draw your attention to the sad history of Pat's morbid
> >obsession with DLs. I had hoped that having recognised the problem [1]
> >(the first and hardest step) he would by now be well on the road to
> >recovery. Sadly, it would appear that this is not the case. In fact
> >this is not Pat's first relapse [2], so perhaps we shouldn't be
> >surprised.
> >
> >Ian
> >
> >[1] http://lists.w3.org/Archives/Public/www-webont-wg/2002Sep/0411.html
> >[2] http://lists.w3.org/Archives/Public/www-webont-wg/2002Dec/0092.html
> 
> Perhaps also not uncharacteristically, Ian manages to simultaneously 
> be insulting, offensively ad-hominem and to mislead the unwary 
> reader.  The acknowledgement in [1] was to a completely unrelated 
> misunderstanding arising in part from my reaction to an extended 
> series of memoranda claiming to show that (what is now called) 
> OWL-Full was impossible, by a specious reference to the set-theoretic 
> paradoxes, but also in part, I concede, from my own ignorance of DL 
> metatheory at that time. The opinions I expressed in [2] are 
> unrelated to [1] , are not a 'relapse' - to acknowledge that DLs are 
> a subset of FOL is not to endorse the basing of the entire SW effort 
> on that subset - and I still hold them, and will continue to hold 
> them.
> 
> I won't react to such jibes in future, but the record should be set straight.

Strangely enough, that is exactly what I told myself when I read your
initial email.

The point I was trying to make with my [witty banter|vile character
assassination]* is that, amusing though your ritual DL bashing is, it
obscures the fact that the restriction being discussed here, i.e., not
being able to create a subPropertyOf rdf:type, is nothing to do with
DLs per se, but is required in order to keep the language inside what
I think we agreed to call "conventional" FOL. In fact separating the
syntax of the language from the domain of discourse is fundamental to
most logics.

Ian

* delete as appropriate



> 
> Pat
> 
> >
> >On May 7, Pat Hayes writes:
> >>
> >>  >I realize that everyone is probably beat from that "Classes as
> >>  >Values" discussion in the SWBP, but ... no thoughts on this?
> >>  >
> >>  >Would it be unthinkable to create a subPropertyOf rdf:type?
> >>
> >>  Its explicitly forbidden in OWL-DL by edict of the DL police, but it
> >>  makes perfect semantic sense and could be done in OWL-Full. On the
> >>  other hand, why not just use rdf:type? What do you gain from the
> >>  explicit subpropertying?
> >>
> >>  If you thought to sneak past the DL syntax restrictions, forget it.
> >>  The DL police have already thought of all the tricks you could use
> >>  and blocked all the exits.
> >>
> >>  Pat
> >>
> >>  >Something like ...
> >>  >
> >>  ><owl:ObjectProperty rdf:ID="hasGenre">
> >>  >    <rdfs:subPropertyOf rdf:resource="&rdf;type"/>
> >>  ></owl:ObjectProperty>
> >>  >
> >>  ><ex:Song rdf:ID="PurpleHaze">
> >>  >    <ex:hasGenre rdf:resource="&ex;ClassRockMusic"/>
> >>  ></ex:Song>
> >>  >
> >>  >Thus, the Individual "PurpleHaze" is an instance of both Song and
> >>  >ClassicRockMusic.
> >>  >
> >>  >Note that the intent is state class membership, not to say that the
> >>  >"subject" of the Song is a concept denoted by a Class (as in the
> >>  >"Classes as Values" paper).
> >>  >
> >>  >--- Stephen
> >>  >
> >>  >
> >>  >On Apr 24, 2004, at 4:50 PM, Stephen Rhoads wrote:
> >>  >
> >>  >>
> >>  >>Folks,
> >>  >>
> >>  >>There are various parts of my (Media Publishing and Distribtuion)
> >>  >>ontology where I would like to avoid the requirement of "multiple
> >>  >>typing".  The objective here is to simplify the ontology and user
> >>  >>interfaces which employ it.
> >>  >>
> >>  >>A user of the ontology should be able to simply declare an
> >>  >>Individual to be a Song, Album, Movie, MovieSeries,
> >>  >>TelevisionProgram, TelevisionSeries, RadioProgram or RadioSeries.
> >>  >>Other important class membership should be inferred by property
> >>  >>values.  A TelevisionSeries, for example, could have
> >>  >>"hasSeriesType" of "SeasonalSeries" and thus be a member of that
> >>  >>Class.  A Movie could have "hasGenre" of "Drama" and thus be a
> >>  >>Drama.
> >>  >>
> >>  >>The problem is that I can't see how to model this without landing
> >>  >>in OWL Full.  Take the following example:
> >>  >>
> >>  >>A sample Class hierarchy:
> >>  >>
> >>  >>Music
> >>  >>    ElectronicMusic
> >>  >>    PopMusic
> >>  >>    RockMusic
> >>  >>       ClassicRockMusic
> >>  >>       GlamRockMusic
> >>  >>       GrungeRockMusic
> >>  >>
> >>  >>And sample Class description:
> >>  >>
> >>  >><owl:Class rdf:ID="ClassicRockMusic">
> >>  >>    <rdfs:subClassOf rdf:resource="#RockMusic"/>
> >>  >>    <owl:equivalentClass>
> >>  >>       <owl:Restriction>
> >>  >>          <owl:onProperty rdf:resource="#hasGenre"/>
> >  > >>          <owl:hasValue rdf:resource="#ClassicRockMusic"/>
> >>  >>       </owl:Restriction>
> >>  >>    </owl:equivalentClass>
> >>  >></owl:Class>
> >>  >>
> >>  >>In other words, if the Individual (a Song or Album) hasGenre
> >>  >>ClassicRockMusic, then it *is* ClassicRockMusic (or at least a
> >>  >>member of a Restriction Class with the same class extension).  But
> >>  >>(I think) this puts the ontology into OWL Full because
> >>  >>ClassicRockMusic is being treated as both a Class and an Individual
> >>  >>(I can confirm that Racer will not accept the ontology from Protege
> >>  >>because it is "not in OWL DL").
> >>  >>
> >>  >>Thoughts?  Solutions?
> >>  >>
> >>  >>--- Stephen
> >>
> >>
> >>  --
> >>  ---------------------------------------------------------------------
> >>  IHMC	(850)434 8903 or (650)494 3973   home
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> >>  phayes@ihmc.us       http://www.ihmc.us/users/phayes
> >>
> 
> 
> -- 
> ---------------------------------------------------------------------
> IHMC	(850)434 8903 or (650)494 3973   home
> 40 South Alcaniz St.	(850)202 4416   office
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> 
Received on Tuesday, 11 May 2004 14:37:59 UTC

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