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Re: What is the most common type of collection or container?

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Mon, 10 Nov 2003 13:01:53 +0200
To: ext Graham Klyne <GK@ninebynine.org>, <jimbobbs@hotmail.com>, <www-rdf-interest@w3.org>
Message-ID: <BBD53CC1.4B74%patrick.stickler@nokia.com>

On 2003-11-10 11:56, "ext Graham Klyne" <GK@ninebynine.org> wrote:

> 
> I tend to use the collection syntax, because they're "closed"

This is actually a claim that has been bugging me for some time. From what
I can see, unless you manage the source of every statement, such that you
can differentiate between one assertion and another based on their source
(and thereby, authority, trustworthiness, etc.), the best you can do is
identify a conflict in the definition of a collection, but you'd not be able
to resolve it. You'd e.g. have multiple assertions for rdf:first or rdf:next
and even though you know they can't all be right, you wouldn't know *which*
was right.

RDF Lists aren't really "closed" (i.e. immutable).

There are various ways (e.g. via an API or inference rules) where a list
can be made ambiguous by having additional rdf:next and rdf:first assertions
made (avoiding the issue of whether one *should* modify lists in that
manner, simply focusing on the fact that one *can* modify lists in that
manner) in which case, the perception that lists are "immutable" is simply
an illusion. To restrict a collection of members to a particular set, even
when using RDF lists, requires tracking of the source as well as selection
of assertions based on source (or authority/trustworthiness inferred based
on source). 

The interesting point here, is that if you go so far as to track the source
of statements and are able to focus on only those statements from trusted
sources/authorities, you have *no* need for explicitly structured
collections, since one can simply query for all rdf:member values
for a particular collection resource where the source is trusted, or
even from a particular named source.

So, RDF lists continue to strike me as providing lots and lots of triples
with no actual benefit over implicit collections based on simple "flat"
membership assertion.

We should have deprecated all of the collections, rather than creating
yet another one that fails to actually provide the functionality that
motivated its creation in the first place -- i.e. immutability.

Oh well... water under the bridge...

Cheers,

Patrick
Received on Monday, 10 November 2003 06:04:13 GMT

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