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Re: owl:hasValue range?

From: Benjamin Nowack <bnowack@appmosphere.com>
Date: Tue, 18 May 2004 12:40:33 +0200
To: Dan Brickley <danbri@w3.org>
Cc: www-rdf-logic@w3.org
Message-ID: <PM-EH.20040518124033.7A5E4.1.1D@192.168.27.2>

On 17.05.2004 19:41:26, Dan Brickley wrote:
>
>I'm trying to understand how to use 'hasValue' when the values
>I have in mind are literals.
>
>http://www.w3.org/TR/2004/REC-owl-ref-20040210/#ValueRestriction 
>suggests this is feasible. 
>
>http://www.w3.org/2002/07/owl says:
>
><rdf:Property rdf:ID="hasValue">
>  <rdfs:label>hasValue</rdfs:label>
>  <rdfs:domain rdf:resource="#Restriction"/>
></rdf:Property>
>
>I'm left puzzled, I guess because I thought OWL DL generally frowned on 
>properties which could point either to a resource or a literal. Maybe 
>built-in properties are excused from this?
>
>Are both the following ok?:   
>
><owl:Restriction>
>  <owl:onProperty rdf:resource="#hasParent" />
>  <owl:hasValue rdf:resource="#Clinton" />
></owl:Restriction>
>
><owl:Restriction>
>  <owl:onProperty rdf:resource="#hasParentName" />
>  <owl:hasValue>Bill Clinton</owl:hasValue>
></owl:Restriction>
>
seems fine to me. you may add datatype information for a
more precise description, although it may be sufficient
to have it in the property and range definition, e.g.:

<owl:Restriction>
  <owl:onProperty rdf:resource="#hasParentName" />
  <owl:hasValue rdf:datatype="&xsd;string">Bill Clinton</owl:hasValue>
</owl:Restriction>

and/or

<owl:DatatypeProperty rdf:ID="hasParentName">
  <rdfs:domain rdf:resource="#Person"/>
  <rdfs:range rdf:resource="&xsd;string"/>
</owl:DatatypeProperty>

a related NOTE in the ref doc says
[[
for datatypes "semantically equal" means that the lexical
representation of the literals maps to the same value
]]

I don't know, if something like

"1.0"^^xsd:float
is "semantically equal" to
"1.0"^^xsd:string

or, in the example above, if

"Bill Clinton"^^rdfs:Literal
is "semantically equal" to
"Bill Clinton"^^xsd:string.

I assume it is.

hm, and what about

"1.0"^^xsd:float vs. "1"^^xsd:integer?

I guess, property values have to be validated/adjusted
against the intended range datatype before a hasValue
restriction can be checked..

now I'm left puzzled as well.. ;)
benjamin

--
Benjamin Nowack

Kruppstr. 100
45145 Essen, Germany

>thanks for any advice,
>
>Dan
>
Received on Tuesday, 18 May 2004 06:40:14 UTC

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