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Re: daml:item - still confused

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Mon, 07 Jul 2003 11:36:36 -0400
Message-ID: <3F099384.D91BD944@cse.lehigh.edu>
To: Jim Hendler <hendler@cs.umd.edu>
CC: webont <www-webont-wg@w3.org>

I think we need to cautious about adding daml:item. I can see people
seeing it, and thinking that it provides an alternative syntax for
building new closed lists, along the lines of:

<owl:Class rdf:ID="WineColor">
    <rdfs:subClassOf rdf:resource="#WineDescriptor" />
    <owl:oneOf>
      <rdf:List>
         <owl:item rdf:resource="#White" />
         <owl:item rdf:resource="#Rose" />
         <owl:item rdf:resource="#Red" />
      </rdf:List>
    </owl:oneOf>
</owl:Class>

Note that many may think that this says that WineColor must be White,
Red or Rose, but instead it simply says that that WineColor must be from
a list that includes White, Red, Rose, and possibly others. This is very
subtle and unintuitive, meaning it could lead to lots of
interoperability problems down the road.

However, if we decided we could live with this, wouldn't such a feature
be better in RDF? After all, that's where the rest of the closed list
stuff is (i.e., rdf:List, rdf:first, rdf:rest).

Jeff

Jim Hendler wrote:
> 
> OK, history is we received a request from Bijan Parsia to add
> daml:item to OWL.  I passed his mail to the group [1] - he explained
> that DAML-S finds daml:item important because they need to be able to
> build "typed lists".
>  Jeremy responded [2] to point out that if we added this it would be
> to Full, not DL, since DL doesn't allow the use of lists.  Jeremy is
> correct, but that doesn't answer the question - Bijan didn't ask to
> add it to DL, he asked to add it to OWL (i.e. Full would address his
> issue).
>  Today I said on the telecon that I thought this related to the issue
> of lists, and was told it didn't - but all the previous email about
> this issue has been in the context of lists, and we have it indexed
> under issue 5.5 which is the issue of lists.
>  So I would like to ask if anyone would actually oppose the addition
> of owl:item to Owl Full.  Otherwise I will (in separate email) propose
> we open issue 5.5, add to the closing text the inclusion of owl:item
> in Owl Full, and then reclose the issue.
>   -JH
> 
> [1]
> http://lists.w3.org/Archives/Public/www-webont-wg/2003Jun/0290.html
> [2]
> 
> --
> 
> 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
> ***
Received on Monday, 7 July 2003 11:36:40 GMT

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