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range, domain and sub-property hierarchies

From: Vlad SIMIONESCU <vsimionescu@softwin.ro>
Date: Tue, 8 Oct 2002 16:17:14 +0200
To: <www-rdf-comments@w3.org>
Message-ID: <000001c26ed5$6724ce70$b5ea66c2@vsimionescu>

I have a question regarding the note from
RDF Vocabulary Description Language 1.0: RDF Schema

namely:

Note: range, domain and sub-property hierarchies

Sub-property hierarchies can be used to express hierarchies of range and
domain constraints. All rdfs:range and rdfs:domain properties that apply to
an RDF property also apply to each of its sub-properties.


I may be misunderstanding something, but cannot it be possible for a
property p to have say classes D1 and D2 as its domain and R1 and R2 as its
range, whereas a subproperty s of p have only D1 as domain and R1 as range ?
If so, the above note is not correct for p and s, since rdfs:domain (p) = R2
is true but rdfs:domain (s) = R2 is false.

As an example, consider a bag like:


<rdf:Bag ID="my_bag">
  <rdf:li resource="my_r1" />
  <rdf:li resource="my_r2" />
</rdf:Bag>

<rdf:Description id="my_r1" rdf:type="my_class1" />
<rdf:Description id="my_r2" rdf:type="my_class2" />


In this example, the range of rdfs:_1 is my_class1, the range of rdfs:_2 is
my_class2 and the range of rdfs:member is my_class1 and my_class2.

The note would always be correct if rephrased like:

Sub-property hierarchies can be used to express hierarchies of range and
domain constraints. All rdfs:range and rdfs:domain properties that apply to
an RDF sub-property of a property also apply to the property.

Thank you

Vlad Simionescu
Analyst

SOFTWIN

Software & Services

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e-mail: vsimionescu@softwin.ro

tel.: (+ 40) 21 233 07 80

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Received on Tuesday, 8 October 2002 09:28:16 GMT

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