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Word of the day: "Negative Triples"

From: XUL Planet | Querying RDF Datasources

var target = datasource.GetTarget(karen, name, true);

You might have noticed that the GetTarget method has a third argument which is set to true above. This is used to indicate whether you want to retrieve a negative triple instead of a normal one. This is a special Mozilla-specific feature that allows an RDF statement to be false instead of true. Remember that when a piece of information is not supplied in the datasource, it means that the datasource does not know that information, not that the information is blank. For instance, if we hadn't specified Karen's name in the RDF/XML, it means that Karen's name is not known to the datasource. She may still have a name however.

A negative triple indicates that a particular statement is not true. For instance, we could add a statement that Karen's name is not 'Tracy'. Note that there is no way to actually specify this in the RDF/XML, only by directly manipulating the datasource. However, negative triples should generally be avoided. They don't really offer a lot of value and usually this kind of information is better specified in other ways.

It would be interesting to know how much these negative triples are/were actually used in Mozilla/Firefox and what for. Once there is a way to take triples away you could do incremental updates of RDF datasources if needed.

A related conversion, from #swig logs (2007-06-28 @ 14:32:36):

< TipTop> how to say that a statement is invalid, for example, without reification?

< timbl> have to either do reification properly, or you use N3 formulas.
< timbl> { Sky clor blue } a log:Falsehood.
< timbl> is the latter.

Tags: mozilla | n3 | rdf | xul