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Re: Comments on informal meaning of the RDFS vocabulary

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Wed, 29 Jan 2003 22:12:15 +0000
Message-Id: <5.1.0.14.0.20030129214951.0ce9b278@localhost>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org

At 16:03 29/01/2003 -0500, Peter F. Patel-Schneider wrote:

[...]

> >
> > >The implementor may decide that RDF
> > >lists have unique firsts and rests and write an RDF system 
> accordingly.  The
> > >user may believe that RDF lists must always have unique firsts and rests.
> >
> > That is clearly the design centre.  What text in the schema doc is
> > incorrect[?]
>
>The following text (emphasis added)
>
>         5.2.2 rdf:first
>
>         rdf:first is an instance of rdf:Property that is used to indicate
>         *the* first item of a list.

Ha!  Phrases including the words "hoist" and "petard" come to mind unbidden :)

Can I find more wiggle room here than there is around owl:Class?

The text here is not false.  rdf:first is used to indicate *the* first item 
of a list, i.e. where the list is "well formed".  The text does not 
preclude the list not being "well formed".

Might your concern be addressed if the text were modified to include a 
discussion of well formed and not well formed lists.  I'd probably need 
some help with the wording, but something along the lines of:

[[
A rdf:List is well formed if it meets either of the following conditions:

   o it is rdf:nil
   o - it has exactly one rdf:first property,
     - and it has one rdf:rest property
     - and the value of its rdf:rest property is a well formed list.

This section describes the meaning of well formed lists.  Whilst an RDF 
graph may contain lists that are not well formed, this is strongly 
discouraged and the meaning of such lists is not described in this document.
]]

Brian
Received on Wednesday, 29 January 2003 17:11:18 GMT

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