Conjunction in SPARQL query using OWL and RDF

Question

I wanted to query the movies that have the highest number of shared type with Matrix movie.

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX owl: <http://www.w3.org/2002/07/owl#>

SELECT ?movie_name (count(distinct ?atype) as ?numatype)
FROM <http://dbpedia.org/>
WHERE {

?movie rdf:type dbo:Film;
       rdf:type ?ftype.

dbr:The_Matrix rdf:type ?ttype.

?atype a owl:class;
       owl:intersectionOf [?ftype ?ttype].


?movie rdfs:label ?movie_name.
FILTER (LANG(?movie_name)="en").
}
GROUP BY ?movie_name 
ORDER BY DESC(?numatype)
LIMIT 100

I defined ?ttype as the type for The matrix movie and ?ftype as the type of ?movie.

when I query this in http://dbpedia.org/sparq there are no results.

Answer 1

The idea is to use a simple join on the types:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX dbo: <http://dbpedia.org/ontology/>

SELECT (SAMPLE(?l) as ?movie_name) 
       (count(distinct ?ttype) as ?numSharedTypes) 
WHERE {
  VALUES ?s {dbr:The_Matrix}
  ?s a ?ttype .
  ?movie a dbo:Film ;
         a ?ttype .
  FILTER(?movie != ?s)
  ?movie rdfs:label ?l .
  FILTER (LANGMATCHES(LANG(?l), 'en'))
}
GROUP BY ?movie
ORDER BY desc(?numSharedTypes)
LIMIT 100

The JOIN itself might be expensive, thus, you could get a timeout resp. due to the anytime feature of Virtuoso get an incomplete result back.

It looks like the query optimizer isn't that smart enough, especially the labels make the performance worse. A bunch of sub-SELECTs make it much faster, although more complex in reading the query:

PREFIX  dbo:  <http://dbpedia.org/ontology/>
PREFIX  rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX  dbr:  <http://dbpedia.org/resource/>

SELECT  ?movie_name ?numSharedTypes
WHERE
  { ?movie  rdfs:label  ?l
    FILTER langMatches(lang(?l), "en")
    BIND(replace(replace(str(?l), "\\(film\\)$", ""), "[^0-9]*\\sfilm\\)$", ")") AS ?movie_name)
    { SELECT  ?movie (COUNT(?type) AS ?numSharedTypes)
      WHERE
        { ?movie  rdf:type  dbo:Film ;
                  rdf:type  ?type
          { SELECT  ?type
            WHERE
              { dbr:The_Matrix rdf:type  ?type
              }
          }
          FILTER ( ?movie != dbr:The_Matrix )
        }
      GROUP BY ?movie
      ORDER BY DESC(?numSharedTypes) ASC(?movie)
      LIMIT   100
    }
  }
ORDER BY DESC(?numSharedTypes) ASC(?movie_name)

Result (chunk):

+------------------------+----------------+
|       movie_name       | numSharedTypes |
+------------------------+----------------+
| The Matrix Reloaded    |             36 |
| The Matrix Revolutions |             33 |
| The Matrix (franchise) |             30 |
| Demolition Man         |             28 |
| Freejack               |             28 |
| Conspiracy Theory      |             27 |
| Deep Blue Sea (1999)   |             27 |
| Fair Game (1995)       |             27 |
| Judge Dredd            |             27 |
| Revenge Quest          |             27 |
| Screamers (1995)       |             27 |
| Soldier (1998)         |             27 |
| The Invasion           |             27 |
| Timecop                |             27 |
| Total Recall (1990)    |             27 |
| V for Vendetta         |             27 |
| Assassins              |             26 |
| ...                    |            ... |
+------------------------+----------------+