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Re: Are literals owl:Things?

From: Antoine Zimmermann <antoine.zimmermann@deri.org>
Date: Sun, 10 Oct 2010 23:59:14 +0200
Message-ID: <4CB23732.6010504@deri.org>
To: Jesse Weaver <weavej3@rpi.edu>
CC: semantic-web@w3.org
Le 08/10/2010 18:39, Jesse Weaver a écrit :
> Semantic Web Mailing List,
>
> I was recently asked a question by a former colleague about whether
> literals are considered owl:Things. Initially, my intuition was that
> literals are rdfs:Resources but they are not owl:Things. However, having
> looked into the matter more closely, I think I have come to a different
> conclusion which I would like to sanity check with the semantic web
> community. Are the following statements true?
>
>
> Under OWL 1 Direct Model-Theoretic Semantics, literals are not owl:Things.
> (EC(owl:Thing) = O where O is a subset of R that is disjoint from LV [1].)

Correct. This is still true in OWL 2.

> Under OWL 1 RDFS-Compatible Semantics, literals are owl:Things for OWL 1
> Full and not for OWL 1 DL.

Exactly. Idem in OWL 2.

> (CEXT_I(S_I(owl:Thing)) = IOT [2], where IOT = R_I for OWL Full [3] and
> IOT is disjoint with LV_I for OWL DL [4].)
>
> Under OWL 2 Direct Semantics, literals are not owl:Things.
> ((owl:Thing)^C = \Delta_I where \Delta_I is disjoint with \Delta_D [5].)
>
> Under OWL 2 RDF-Based Semantics, literals are owl:Things.
> (ICEXT(I(owl:Thing)) = IR [6].)

You are right. There are some differences between the direct semantics 
(DL-based) and the RDF-based semantics.

So the conclusion is that literals are not owl:Thing under the direct 
(Description-Logics-based) semantics but are owl:Thing under the 
RDF-based semantics. This might look like a significant problem but in 
practical case it seems that it does not affect much the 
interoperability of DL and non-DL tools, as far as I can tell.


AZ.

> [1] http://www.w3.org/TR/owl-semantics/direct.html#3.1
> [2] http://www.w3.org/TR/owl-semantics/rdfs.html#5.2
> [3] http://www.w3.org/TR/owl-semantics/rdfs.html#5.3
> [4] http://www.w3.org/TR/owl-semantics/rdfs.html#5.4
> [5] http://www.w3.org/TR/owl2-direct-semantics/#Interpretations
> [6]
> http://www.w3.org/TR/owl2-rdf-based-semantics/#Semantic_Conditions_for_the_Vocabulary_Classes
>
>
>
> Jesse Weaver
> Ph.D. Student, Patroon Fellow
> Tetherless World Constellation
> Rensselaer Polytechnic Institute
> http://www.cs.rpi.edu/~weavej3/index.xhtml
>
>
Received on Sunday, 10 October 2010 22:00:02 UTC

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