- From: Jan Michelfeit <michelfeit.jan@gmail.com>
- Date: Mon, 03 Jun 2013 23:39:59 +0200
- To: public-lod@w3.org
Hi,
thank you all for your answers.
> ... One "represents" a null by failing to include the relationship
> ... RDF semantics make no assumptions about what the absence of a proposition/statement means
I agree. The question was actually about *distinguishing* between the mentioned cases.
>From your suggestions and a quite comprehensive answer at SO [1], I see these solutions:
(1) Use ontology to specify proper constraints. This may be cardinality of the questioned property or, as suggested by Phillip, assertion "that anything with a year of death is necessarily a dead person".
(2) Use an RDF container and possibly rdf:nil (thanks to Barry and Robert for his example) .
(3) Use a blank node to give more details about the questioned value. Examle [2]:
:foo :aProp [a :nullableValue; rdf:value "value"] ;
:bProp [a :nullableValue; :reason :notAvailable ]
Regards,
Jan
[1] http://stackoverflow.com/a/16889273/2032064
[2] http://stackoverflow.com/a/16898786/2032064
Received on Monday, 3 June 2013 21:41:19 UTC