How to get the path details between two nodes in DBpedia in SPARQL

Question

I want to check if two DBpedia nodes have a path using;

• dct:subject and skos:broader properties
• without specifying properties

For instance consider the two DBpedia nodes http://dbpedia.org/resource/Cat and http://dbpedia.org/resource/Dog. I tried to use the following wildcard query to do it.

ASK {
  <http://dbpedia.org/resource/Cat> ((<>|!<>)|^(<>|!<>))* <http://dbpedia.org/resource/Dog> 
}

However, I get a memory error. I am wondering if there is a more suitable way of doing this in sparql.

I am happy to provide more details if needed.

Answer 1

Your question shows <> which is not a valid property or wildcard.

You cannot use property variables (wildcards) in property paths.

So you need to understand the structure of how dct:subject and skos:broader are used, and exploit that. I happen to know that

• dct:subject links pages to categories
• skos:broader makes the category hierarchy

I should warn you that the wikipedia category hierarchy is vast and diverging. Eg see "Domain-specific modeling: Towards a Food and Drink Gazetteer" (Slides, pdf, published).

You don't want to use skos:broader*, instead use Transitive reasoning and skos:broaderTransitive (eg get our GraphDB Free edition). So you can try

select * {
  ?cat skos:subject/skos:broaderTransitive ?x.
  ?dog skos:subject/skos:broaderTransitive ?x.
}

but because of the vast and diverging structure, this will take a LOT of time and return lots of cats, many of them barely relevant.