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Re: Efficient context mechanisms

From: Seth Russell <seth@robustai.net>
Date: Tue, 14 Jan 2003 11:31:19 -0800
Message-ID: <3E246587.10600@robustai.net>
To: Bob MacGregor <macgregor@ISI.EDU>
CC: Dave Reynolds <der@hplb.hpl.hp.com>, www-rdf-interest@w3.org, tar@ISI.EDU, hans@ISI.EDU

Bob MacGregor wrote:

> If we were using a quad representation, then memory is linear in
> the number of quads.  However, wrt quads, I'm not sure our notion is
> in sych with the statings crowd.  Suppose the quad form is
> [C1 S P O]
> [C2 S P O]
> [C3 S P O]
> While we conceptualize this as one triple [S P O], asserted
> in three different contexts, the statings crowd seems two think of
> these quads as three different statings that are only loosely
> related. 

I missed it, what is not in sync with the stating crowd (you count me in 
that context) ?

> What the semantics of the above is can't really be resolved unless we
> decide on what a quad is (for example, must one of its arguments always
> be a context?) and what a context is (e.g., is a context a set of
> assertions or a set of statings?). 

I think we need two concepts here:  Model, and Context.   A model 
(sometimes called a graph) is just a collection of triples - nothing 
more, nothing less.  To be completely general I wouldn't even attach any 
notion of Truth to the collection - often we collect triples without 
regard to whether they are true or not.   A Context is a Model, but a 
Context may contain other properties, amoung which might be:  1) the 
agent or agents who collected the triples and 2) some other object 
(resource, purpose, catagory, whatever ...) that the context is about.  

To summarize and answer your specific questions according to my 

1)  The fourth URI  or blank node identifier of a Quad must always 
identify a Model.
2)  A model is a set (collection?) of statings.
3)  A Context is a Model that has been further adapted to serve the 
needs of a specific group of agents or applications or purposes or 

Check out <http://topicexchange.com/> , is that application starting to 
establish Contexts ?  

Seth Russell
Received on Tuesday, 14 January 2003 14:31:53 UTC

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