Question

Are there practical use cases for negated SPARQL property paths?

I use sparql property paths regularly, but I recently realized that I never seem to have a use for the negation operator, which matches a path if it does not involve the specified property or property set.

?source !ex:property ?target

Unlike the case with negated character ranges ([^abcd]) for text search, I can't seem to think of any use cases that would need this. The example in the SPARQL Recommendation is no help:

Negated Property Paths: Find nodes connected but not by rdf:type (either way round):

 { ?x !(rdf:type|^rdf:type) ?y }

Research: I found this SO answer where it's used to work around the lack of variables in sparql path by matching for (x or !x). But this only uses negation for lack of anything more appropriate.

So are there realistic use cases that I am overlooking, where one needs to look for all-but a certain property or property set in a path? Or is the negation operator hardly ever used in practice?

 2  45  2
1 Jan 1970

Solution

 1

One possible use case in which this syntax could be used is some form of schema validation. As for me, sometimes I use it in Wikidata to check whether entities that should be used only for internal purposes are indeed utilised correctly. For example, wd:Q28091153 should only be specified as object for pq:P2241. Thus, for identifying possible bad usages one can search for ?x !pq:P2241 wd:Q28091153.

2024-07-24
logi-kal