Re: Representing NULL in RDF

On 03/06/13 16:52, Phillip Lord wrote:
> Value unknown is easy. Just don't say anything.
> Value not applicable and doesn't exist, given your examples, seem the
> same to me.

I don't agree. Under the Open World assumption anything that can later 
be learned should not affect consistency. A positive null ("there is no 
such") should lead to a contradiction is someone later asserts such a 
value/relationship (which doesn't happen with a simple unpopulated 
relationship from the subject).

In RDF (which has been my answer before - feel free to contradict me, 
I'm not an authority, it's just that I've made the proposal before) this 
seems possible only with Collections. What I mean by this is that with a 
list-ranged relationship I can specify a value of 'there is no such' 
(rdf:nil) and someone trying to populate the list later would have to 
revert that fact to provide such a value. Without a list expected, this 
does not seem possible (again, to me).


Received on Monday, 3 June 2013 20:58:49 UTC