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Re: Correct Usage of rdfs:idDefinedBy in Vocabulary Specifications with a Hash-based URI Pattern

From: Martin Hepp <martin.hepp@ebusiness-unibw.org>
Date: Thu, 30 Sep 2010 14:49:52 +0200
Cc: public-lod@w3.org, pedantic-web@googlegroups.com
Message-Id: <C916F1B0-E19E-4211-9A77-142F7B1A36EF@ebusiness-unibw.org>
To: Kingsley Idehen <kidehen@openlinksw.com>
Hi Kingsley,
Thanks - that is what I had assumed.

Note, however, the majority of the Web vocabularies use the same URI  
for the entity name reference and the descriptor reference, see the  
link provided by Michael Hausenblas:

	http://code.google.com/p/void-impl/issues/detail?id=45

and in particular the little survey by Richard Cyganiak posted on that  
page.

I personally would argue that in the case of ontologies /  
vocabularies, the conceptual difference between the entity and the  
descriptor is a lot less significant than when it comes to data, since  
an ontology is, by definition, a specification, i.e. a document.

So both patterns should work in practice, as long as the URI for the  
owl:Ontology instance is the same as the URI used in conjunction with  
rdfs:isDefinedBy.

Martin




On 30.09.2010, at 12:59, Kingsley Idehen wrote:

> On 9/30/10 3:06 AM, Martin Hepp wrote:
>> Dear all:
>>
>> We use rdfs:isDefinedBy in all of our vocabularies (*) for linking  
>> between the conceptual elements and their specification.
>>
>> Now, there is a subtle question:
>>
>> Let's assume we have an ontology with the main URI
>>
>>    http://purl.org/vso/ns
>>
>> All conceptual elements are defined as hash fragment URIs (URI  
>> references), e.g.
>>
>>    http://purl.org/vso/ns#Bike
>>
>> The ontology itself (the instance of owl:Ontology) has the URI
>>
>>    http://purl.org/vso/ns#
>>
>> <http://purl.org/vso/ns#>  a owl:Ontology ;
>>    owl:imports <http://purl.org/goodrelations/v1> ;
>>    dc:title "VSO: The Vehicle Sales Ontology for Semantic Web-based  
>> E-Commerce"@en .
>>
>> So we have two URIs for the ontology:
>>
>> 1. http://purl.org/vso/ns# for the ontology as an abstract artefact
>> 2. http://purl.org/vso/ns for the syntactical representation of the  
>> ontology (its serialization)
>
> Yes, you have two HTTP URIs associated with the Ontology. One is the  
> "Name" of the Ontology Entity (Thing) and the other is the  
> "Address" (URL) of the Ontology Descriptor Resource. Thus:
>
> 1. http://purl.org/vso/ns# -- Entity Name Reference
> 2. http://purl.org/vso/ns -- Descriptor Resource Address Reference .
>
>>
>> Shall the rdfs:isDefinedBy statements refer to #1 or #2 ?
>>
>> #1
>> vso:Vehicle a owl:Class ;
>>    rdfs:subClassOf gr:ProductOrService ;
>>    rdfs:label "Vehicle (gr:ProductOrService)"@en ;
>>    rdfs:isDefinedBy <http://purl.org/vso/ns#> . <===========
>>
>> #2
>> vso:Vehicle a owl:Class ;
>>    rdfs:subClassOf gr:ProductOrService ;
>>    rdfs:label "Vehicle (gr:ProductOrService)"@en ;
>>    rdfs:isDefinedBy <http://purl.org/vso/ns> . <===========
>>
>>
>> I had assumed they shall refer to #1, but that caused some debate  
>> within our group ;-)
>
> You refer to Entities (Things) by Name Reference for Linked Data to  
> work i.e. Names resolve to Descriptor Resources which may be  
> serialized from Linked Data Server to User Agent using a variety of  
> data formats such as: HTML+RDFa, RDF/XML, N3/Turtle, N-Triples, TriX  
> etc..
>>
>> Opinions?
>
> Also cc'd in the pedantic web folks for comments :-)
>
>>
>> Best
>>
>> Martin
>>
>>
>>
>
>
> -- 
>
> Regards,
>
> Kingsley Idehen	
> President&  CEO
> OpenLink Software
> Web: http://www.openlinksw.com
> Weblog: http://www.openlinksw.com/blog/~kidehen
> Twitter/Identi.ca: kidehen
>
>
>
>
>
>
Received on Thursday, 30 September 2010 12:50:53 UTC

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