Representing NULL in RDF

I was doing some comparison of relational databases and Linked Data and ran into the problem of representing an equivalent of database NULL in RDF.

I was surprised I haven't found any material or discussion on this topic (found only [1]) - is there some?. I believe it would be beneficial if this question was answered somewhere for future reference. I started a question on Stack Overflow [2] where I think it will be easier to discover and so that this list won't get polluted.

I'm aware of the open world assumption in RDF, but NULL or a missing value can have several interpretations, for example:

- value not applicable (the attribute does not exist or make sense in the context)
- value uknown (it should be there but the source doesn't know it)
- value doesn't exist (e.g. year of death for a person alive)
- value is witheld (access not allowed)

I would like to known whether there is some *standard or generally accepted* way of distinguishing these cases. If you have an answer, please put it on [2], is possible.

Thanks in advance,
Jan Michelfeit


Received on Monday, 3 June 2013 13:05:34 UTC