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Xtreme Punning

From: Michael Schneider <schneid@fzi.de>
Date: Fri, 11 Jan 2008 10:17:52 +0100
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A05A64EF@judith.fzi.de>
To: "Owl Dev" <public-owl-dev@w3.org>

Here's a little OWL I wrote,
Your reasoner will check it node for node.
Don't worry, it will be happy!

    ex:foo rdf:type ex:foo .
    ex:foo ex:foo ex:foo .
    ex:foo ex:foo "ex:foo"^^ex:foo .

When thinking about punning in OWL-1.1-DL, I always differentiated between
two "kinds" of punning:

    * punning between individuals and classes,

    * punning between data properties and object properties.

But shouldn't it be allowed to pun on /each/ combination of types, for
example both on classes and on object properties? The current OWL-1.1
working drafts seem to suggest this, or at least do not forbid it: 

 
<http://www.w3.org/TR/2008/WD-owl11-semantics-20080108/#Model-Theoretic_Sema
ntics_for_OWL_1.1>

    "[...] the same name can be used in an ontology
    to denote a class, a datatype, a property (object or data), 
    an individual, and a constant."

If this is possible, I do not see why the application of punning should be
restricted to only /two/ types in a given ontology. So it looks to me that
my somewhat contrived (I admit! :)) example above really is a syntactically
valid (and even semantically consistent) OWL-1.1-DL ontology. At least, a
reasoner shouldn't have any problems to clearly distinguish between the
different occurrences of 'ex:foo', and it should easily be able to infer the
following (omitted above) typing axioms:

    ex:foo rdf:type owl:Thing .
    ex:foo rdf:type owl:Class .
    ex:foo rdf:type owl:ObjectProperty .
    ex:foo rdf:type owl:DataProperty .
    ex:foo rdf:type rdfs:Datatype .

If my conjecture is correct, then it probably wouldn't make too much sense
to discuss whether a single "punning kind" like data/object property punning
should be dropped from the OWL-1.1-DL draft or not (the OWL-WG had such a
discussion this week), since it is then only one combination of many
possible:

                          | IND CLS OPR DPR DTP
    -------------------------------------------
    IND (individual)      | 
    CLS (class)           |  X
    OPR (object property) |  X   X
    DPR (data property)   |  X   X   X
    DTP (data type)       |  X   X   X   X 


Do pun, have fun! ;-)
Michael

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
Tel  : +49-721-9654-726
Fax  : +49-721-9654-727
Email: Michael.Schneider@fzi.de
Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555

FZI Forschungszentrum Informatik an der Universität Karlsruhe
Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
Tel.: +49-721-9654-0, Fax: +49-721-9654-959
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Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus
Received on Friday, 11 January 2008 09:18:02 GMT

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