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Re: [updated] EARL 1.0 Schema

From: Johannes Koch <johannes.koch@fit.fraunhofer.de>
Date: Wed, 25 Feb 2009 13:40:02 +0100
Message-ID: <49A53C22.9010701@fit.fraunhofer.de>
To: ERT WG <public-wai-ert@w3.org>
Shadi Abou-Zahra schrieb:
>>> Another approach could be to keep both the domain and the range of 
>>> the earl:mainAssertor property to be earl:Assertor (as currently 
>>> defined). This would mean that both the subject and the object in 
>>> such a triple would always be of type earl:Assertor.
>>
>> Given the following triple
>>
>> <#someAssertor> earl:mainAssertor <#someOtherAssertor>
>>
>> With earl:mainAssertor being a sub-property of foaf:member and having 
>> the domain and range earl:Assertor, this would imply the following 
>> additional triples:
>>
>> <#someAssertor> rdf:type <earl:Assertor>
>> <#someAssertor> rdf:type <foaf:Group>
>> <#someOtherAssertor> rdf:type <earl:Assertor>
>> <#someOtherAssertor> rdf:type <foaf:Agent>
> 
> Note: #someAssertor and #someOtherAssertor are not necessarily of type 
> earl:Assertor in this case (it would depend on the other triples).

Because earl:mainAssertor's domain and range are earl:Assertor, every 
subject and object in a triple with an earl:mainAssertor predicate 
becomes implicitly of type earl:Assertor.

See <http://www.w3.org/TR/rdf-schema/#ch_range>:

> The triple
> 
>     P rdfs:range C
> 
> states that P is an instance of the class rdf:Property, that C is an instance of the class rdfs:Class and that the resources denoted by the objects of triples whose predicate is P are instances of the class C.

and <http://www.w3.org/TR/rdf-schema/#ch_domain>:

> A triple of the form:
> 
>     P rdfs:domain C
> 
> states that P is an instance of the class rdf:Property, that C is a instance of the class rdfs:Class and that the resources denoted by the subjects of triples whose predicate is P are instances of the class C.


>> I don't see any problem. Resources can have many types.
> 
> I'm not saying that there is a problem but two different solutions. In 
> the first, we ensure that the subjects and objects are type foaf:Group 
> and foaf:Agent, and in the second that they are type earl:Assertor.
> 
> Having said that, the subject will usually be of type earl:Assertor due 
> to the earl:assertedBy property. The object of earl:mainAssertor might 
> not always be type earl:Assertor in the first option.
> 
> Any preferences for the one or other solution?

It's not an "either-or", is it?

According to 
<http://www.w3.org/WAI/ER/EARL10/WD-EARL10-Schema-20090223#mainAssertor> 
earl:mainAssertor

1. has domain earl:Assertor and range earl:Assertor, which makes all 
subjects and objects in earl:mainAssertor triples an earl:Assertor;

_and_

2. is a sub-property of foaf:member (at least that's how I interpret the 
prose), which makes all subjects in earl:mainAssertor triples a 
foaf:Group and all objects in earl:mainAssertor triples a foaf:Agent.

-- 
Johannes Koch
Fraunhofer Institute for Applied Information Technology FIT
Web Compliance Center
Schloss Birlinghoven, D-53757 Sankt Augustin, Germany
Phone: +49-2241-142628    Fax: +49-2241-142065
Received on Wednesday, 25 February 2009 12:40:50 GMT

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