# Re: Collections vs Containers

From: David Menendez <zednenem@psualum.com>
Date: Fri, 14 Nov 2003 21:36:19 -0500
To: Sandro Hawke <sandro@w3.org>, www-rdf-interest@w3.org
Message-ID: <r02000200-1030-7F13A188171411D8B0D8000393758032@[10.0.1.2]>
```
Sandro Hawke writes:

>
>
> >     2. Adding a statement to a graph containing a well-formed
> > collection cannot change that collection *and* leave it well-formed.
>
> Um, sure it can, it just implies some equalities.   But your basic
> point is essentially right, yes.

I'm not sure what you mean. If all it's doing is adding some equalities,
then it isn't changing the collection.

Also, that interpretation assumes that rdf:first and rdf:rest are
functional, which is not supported by any RDF documents I'm aware of.
(In fact, I seem to recall a few stating that the rdf:List vocabulary
also allows for "branching".)

> The essential difference could be made up by
>       S rdf:length "3"^^xsd:int.
>
> That may look ugly to RDF eyes, but any OWL reasoner has to handle
> integer values like that, so it'll get nicer (in our heads or our
> computers; I don't know which :-).
>
> I'm pretty sure I could then write the general  <->  formula,
> given a predicate linking rdf:_<n> to rdf:_<n+1>.

If we had some simple way to define composition, we wouldn't even need
that. Declaring "rdf:_<n+1> == rdf:rest o rdf:_<n> where n > 1" and
"rdf:_1 == rdf:first" isn't that different from declaring "rdf:_<n>
rdfs:subPropertyOf rdf:member"; i.e., you already need special code to
handle it.
--
David Menendez <zednenem@psualum.com> | "In this house, we obey the laws
<http://www.eyrie.org/~zednenem>      |        of thermodynamics!"
```
Received on Friday, 14 November 2003 21:36:12 GMT

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