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Re: GUIDE: Syntax query re parseType=

From: Jeff Heflin <heflin@cse.lehigh.edu>
Date: Fri, 30 Aug 2002 17:23:56 -0400
Message-ID: <3D6FE26C.82E5F0B0@cse.lehigh.edu>
To: "Smith, Michael K" <michael.smith@eds.com>
CC: www-webont-wg@w3.org

I have also come to believe that collection was a bad choice of keyword.
In hindsight, I think "daml:ClosedList" would have made its purpose much
clearer. Does anybody else care enough that I should raise this as an
issue for OWL?

Jeff

"Smith, Michael K" wrote:
> 
> Ok.  I find the choice of keyword bizarre.  Mixing syntax
> and semantics in an odd way.
> 
> So the difference between
> 
>         <daml:oneOf rdf:parseType="daml:collection">
>           <rdf:li> <Person rdf:id="John" /> </rdf:li>
>           <rdf:li> <Person rdf:id="Bill" /> </rdf:li>
>         </daml:oneOf>
> and
>         <daml:oneOf>
>           <rdf:li> <Person rdf:id="John" /> </rdf:li>
>           <rdf:li> <Person rdf:id="Bill" /> </rdf:li>
>         </daml:oneOf>
> 
> is that I can prove that the first one has exactly 2 elements?
> While I can't extend the second one (since I can't reference it), the
> semantics don't require that it be closed.
> 
> -----Original Message-----
> From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com]
> Sent: Thursday, August 29, 2002 9:37 AM
> To: Smith, Michael K
> Cc: www-webont-wg@w3.org
> Subject: Re: GUIDE: Syntax query re parseType=
> 
> From: "Smith, Michael K" <michael.smith@eds.com>
> Subject: GUIDE: Syntax query re parseType=
> Date: Thu, 29 Aug 2002 09:25:04 -0500
> 
> >
> > Help.  I'm trying to explain some syntax in the Guide document.
> >
> > Why do we have rdfs:parseType tacked onto the various set operators?
> > Obviously, we inherited it from DAML+OIL, but I don't understand the need
> > for it there, either.
> >
> > As far as I can tell, it is completely redundant in the XML syntax.  That
> > is, there is no other possible interpretion of the children of oneOf,
> > unionOf, and intersectionOf.
> >
> > What am I missing?
> >
> > - Mike
> 
> The reason for rdf:parseType="daml:collection" is to allow for a convenient
> way of supplying lists.  The problem is that a construct like
> 
>         <daml:oneOf rdf:id="MySet">
>           <rdf:li> <Person rdf:id="John" /> </rdf:li>
>           <rdf:li> <Person rdf:id="Bill" /> </rdf:li>
>         </daml:oneOf>
> 
> is not closed.  Anyone can do something like
> 
>         <daml:oneOf rdf:id="peter:MySet">
>           <rdf:li> <Person rdf:id="Susan" /> </rdf:li>
>         </daml:oneOf>
> 
> to add another element of the set.
> 
> There are very bad consequences of a construct like this.
> 
> To get around this inadequacy of RDF, DAML+OIL has a list construct and
> 
>         <daml:oneOf rdf:parseType="daml:collection">
>                 <Person rdf:id="John" />
>                 <Person rdf:id="Bill" />
>         </daml:oneOf>
> which expands to
> 
>         <daml:oneOf>
>                 <daml:List>
>                         <daml:first>
>                                 <Person rdf:id="John" />
>                         </daml:first>
>                         <daml:rest>
>                                 <daml:List>
>                                         <daml:first>
>                                                 <Person rdf:id="Bill" />
>                                         </daml:first>
>                                         <daml:rest>
>                                                 <daml:list
> rdf:id="daml:nil">
>                                         </daml:rest>
>                                 </daml:List>
>                         </daml:rest>
>                 </daml:List>
>         </daml:oneOf>
> 
> and cannot be non-monotonically messed with.
> 
> (I may have some of the details wrong, but you should be able to get the
> idea.)
> 
> peter
Received on Friday, 30 August 2002 17:24:04 GMT

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