Re: daml:item

At 7:45 PM -0400 5/9/03, Bijan Parsia wrote:
>This could be an RDF issue, but given OWL's relationship to 
>DAML+OIL, I think it could reasonably be handled by WebOnt.
>
>DAML+OIL had daml:item. While not strictly necessary, i've been 
>encountering a fair number of DAML+OIL ontologies which use it, and 
>the alternative formulations (e.g., for typed lists) is fairly 
>cumbersome.
>
>So, I'd like it added back in.
>
>Cheers,
>Bijan Parsia.


Bijan-
  Thanks for your email raising the issue of restoring daml:item.  The 
list constructors were a difficult issue as they impacted both the 
RDF Core and Web Ontology Working Groups, and the issue of whether to 
include an "item" construct was considered by both.  Given the final 
resolution, not to require it in RDF, the WebOnt WG was resistant to 
adding it into OWL [1]. However, we did agree that you make a good 
point about needing to be able to restrict the members of a list to a 
class, and that the means to do that is not obvious.  We therefore 
are adding the following example:

>    <rdfs:Class rdf:ID="OperaList">
>      <rdfs:subClassOf rdf:resource="&rdf;List"/>
>      <rdfs:subClassOf>
>        <Restriction>
>          <onProperty rdf:resource="&rdf;first"/>
>          <allValuesFrom rdf:resource="#Opera"/>
>        </Restriction>
>      </rdfs:subClassOf>
>      <rdfs:subClassOf>
>        <Restriction>
>          <onProperty rdf:resource="&rdf;rest"/>
>          <allValuesFrom rdf:resource="#OperaList"/>
>        </Restriction>
>      </rdfs:subClassOf>
>    </rdfs:Class>

to the reference document (with accompanying text currently being 
produced - see the editor's draft).

  Please let us know if this is adequate in meeting your comment
  Jim Hendler for Web Ont WG

[1] http://lists.w3.org/Archives/Public/www-webont-wg/2003Jul/0069.html

-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  *** 240-277-3388 (Cell)
http://www.cs.umd.edu/users/hendler      *** NOTE CHANGED CELL NUMBER ***