Re: Subtyping existing terms or just using them...

Hi,

Charles McCathieNevile wrote:
> if our idea of a Person is the same as some existing and well-known 
> idea of a Person (let's say FOAF, not to be too hypothetical) then we 
> can make a copy of it and wait for people to implement the OWL 
> properties to realise that this is something that they already know 
> about, or we can just use FOAF, so there is nothing to wait for.

The basic problem is to define some external vocabulary as part of EARL either as optional or required. It seems to be important to have a formal schema that is a complete specification of EARL. The question is how to do this best.

For the specific case of earl:Assertor, I is was thinking of the following type of approach to define it as one of earl:Tool or foaf:Person:

<owl:Class rdf:about="&earl;Assertor">
  <rdfs:label xml:lang="en">Assertor</rdfs:label>
  <rdfs:comment xml:lang="en">Person or Tool that claims assertions</rdfs:comment>
  <owl:oneOf rdf:parseType="Collection">
    <owl:Thing rdf:about="&earl;Tool"/>
    <owl:Thing rdf:about="&foaf;Person"/>
  </owl:oneOf>
</owl:Class>

However, for some other things such as dc:title or dc:date it becomes difficult and tricky to handle sensibly as you point out. For such entities (that are usually required properties), I was thinking that equating to external vocabulary may be useful. For example:

<rdf:Property rdf:about="&earl;ToolName" rdfs:label="Name of a Tool">
  <rdfs:domain rdf:resource="&earl;Tool"/> 
  <owl:sameAs rdf:resource="&dc;title" /> 
</rdf:Property>

Note that the dc:title has not really been redefined or copied with this approach. Merely the name earl:ToolName is used as a placeholder to say that every earl:Tool needs an earl:ToolName (which is nothing else but a dc:title).

PS: We also still need to resolve the issue that most FOAF vocabulary is not yet stable and referenceable but that is a separate issue.

Regards,
  Shadi


-- 
Shadi Abou-Zahra,       Web Accessibility Specialist for Europe 
World Wide Web Consortium (W3C),             http://www.w3.org/ 
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IST WAI-TIES Project (WAI-TIES)     http://www.w3.org/WAI/TIES/ 
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Received on Monday, 23 May 2005 12:06:14 UTC