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RE: An idea I need help with, or told to stop wasting time on!

From: Michael Schneider <schneid@fzi.de>
Date: Sun, 6 Jun 2010 22:58:26 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A001E9975A@judith.fzi.de>
To: <nathan@webr3.org>
Cc: "Linked Data community" <public-lod@w3.org>, <semantic-web@w3.org>
Hi!

Just a few notes concerning your ideas and OWL DL (I don't know whether this
is important for you or not, but some people might find it relevant):

Nathan wrote:

>1: Introduce a 'value' property
>
>Where currently we can say:
>  :me foaf:name 'nathan' .
>
>I'd propose introducing an ex:value property that allows us to say:
>  :me foaf:name [ ex:value 'nathan' ] .
>or
>  :me foaf:name :myname .
>  :myname ex:value 'nathan' .

The FOAF spec defines foaf:name as a owl:DatatypeProperty [1], and therefore
cannot be used in OWL DL with blank nodes (representing anonymous
individuals) or URIs (representing named individuals) in object position. No
problem with RDF(S) or OWL Full, though.

>I'm hoping the basic human understanding of this is pretty obvious,
>sorting out the domain & range of ex:value, class of :myname, ontology
>details and related are hurting my head a bit at the minute.
>
>And thus you could describe a value:
>
>  :me foaf:name [
>      ex:value 'nathan' ;
>      ex:type xsd:string ;

In OWL DL, you cannot use a datatype name in the object position of an
object or data property (ex:type will be either an object property or a data
property). If this was a typo and you really mean "rdf:type", it is still
not allowed in OWL DL, since xsd:string is not a class in OWL DL. Again, it
is fine in RDF(S) or OWL Full.

>And do some funkier stuff:
>
>  :me foaf:mbox :myemail ;
>  :myemail ex:value <mailto:nathan@webr3.org> ;

Above, you use ex:value with literals, but here you use it with a URI. In
OWL DL, you have to decide for one: either ex:value is a data property, then
URIs are not allowed; or it is an object property, then literals are not
allowed. Again, no problems with RDF(S) and OWL Full.

Michael

[1] http://xmlns.com/foaf/spec/20100101.rdf

--
Dipl.-Inform. Michael Schneider
Research Scientist, Information Process Engineering (IPE)
Tel  : +49-721-9654-726
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Email: michael.schneider@fzi.de
WWW  : http://www.fzi.de/michael.schneider
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Received on Sunday, 6 June 2010 20:59:04 GMT

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