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Klyne Contexts: 3. Statements sets in RDF

From: Jonas Liljegren <jonas@rit.se>
Date: 23 Nov 2000 20:09:09 +0100
To: Graham Klyne <GK@Dial.pipex.com>
Cc: RDF interest group <www-rdf-interest@w3.org>, Wraf development <rdf@uxn.nu>
Message-ID: <87zoiqbj56.fsf@astral.paranormal.se>
This is the final part of my comment on the DFD [1].

You are defining a new type of container using rdfc:member instead of
_1, _2, etc.

I think it's redundant to have both systems.  

In Wraf [2] I'm planning to store container members in a special way,
optimized for compact storage and easy manipulation.  With such
optimizations, there is no need for another type of
rdfs:ContainerMembershipProperty.


You write:

        RDF defines a way to represent collections of statements which
        suffers from some practical difficulties:

        1 The rdf:Bag container class and associated containment
          properties make it diffcult to add new statements to a
          collection without knowing about all of the statements
          already belonging to that collection.

        2 It is not possible to represent different containment
          relations for a single container.

        3 The standard container classes have no way to represent
          distributive referents within an RDF graph.

        4 The standard mechanism for collecting reified statements
          (bagId attribute) is bound to documents containing RDF
          statements, and cannot be used for collecting statements
          that are defined across several documents.

        5 The standard mechanism does not allow for a given reified
          statement to belong to more than one collection.

        [[[The final two points above may not be strictly true, but if
        not it is not clear how to use standard RDF to obtain the
        effects described.]]]


Let me comment:

1. With special methods for conatiner handling, you will not have to
   bother about the present content.  Wraf will give each container
   the dynamic property 'size', and methods for adding and quering the
   container without knowing each propertys number.

2. I would say that you can only be in the container in one way.  But
   besides the content, there can be multipple properties describing
   other things, like for a normal resource.  You could also attach
   extra information to each membership statement.

3. Distribution functionality can be added to the standard container.
   Both distribution of properties to each member and distribution of
   all the members properties to the container or other resource.

4. You're right.  This is why Wraf differentiates between Models and
   Selections.  Each model holds the statements from one 'document'
   but can also be contained in several selections.  Wraf's Selections
   is very close to your Contexts.  That's why I'm intrested in them.

5. Well. You could explicitly put a statement in each collection.  But
   that would not be the standard way? :)


Anyway.  My point here is that Wraf uses the "contexts" but name them
selections.  And I found some pointes intresting and will maby
implemnet them.  Maby we could make our schemas more compatible?  I
would like to keep the standard rdfs:ContainerMembershipProperty.



 [1] http://public.research.mimesweeper.com/RDF/RDFContexts.html
 [2] http://www.uxn.nu/wraf/

-- 
/ Jonas Liljegren

The Wraf project http://www.uxn.nu/wraf/
Sponsored by http://www.rit.se/
Received on Thursday, 23 November 2000 14:07:58 GMT

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