使用Sparql获取DBpedia中实体类型之间的所有可能的谓词

Question

I am trying to get all the possible predicates that are possible in between two entity types. Below is the example for two entities with Person type.

SELECT distinct ?p 
WHERE { ?url1 rdf:type <http://dbpedia.org/ontology/Person> . 
        ?url2 rdf:type <http://dbpedia.org/ontology/Person> . 
        ?url1 ?p ?url2 . 
        FILTER(STRSTARTS(STR(?p), "http://dbpedia.org/ontology")).
      }

However, the resulting output consists of predicates like birthPlace , deathPlace which definitely cannot be in between two Person types.

Am I missing any constraints to get more logical outputs?

Answer 1

Not sure whether it's not worth to provide it as an answer ...

You're missing only one point:

The data in DBpedia is not perfect and free of noise since it's automatically extracted from Wikipedia.

You can check why this happens when you use

SELECT * WHERE { 
  ?url1 rdf:type <http://dbpedia.org/ontology/Person> . 
  ?url2 rdf:type <http://dbpedia.org/ontology/Person> . 
  ?url1 <http://dbpedia.org/ontology/birthPlace> ?url2 . 
}
limit 10

Among others, you get

+-------------------------------------------+------------------------------------------------------------------------+
|                   url1                    |                                  url2                                  |
+-------------------------------------------+------------------------------------------------------------------------+
| http://dbpedia.org/resource/Analía_Núñez  | http://dbpedia.org/resource/David                                      |
| http://dbpedia.org/resource/Jorvan_Vieira | http://dbpedia.org/resource/Luís_Alves_de_Lima_e_Silva,_Duke_of_Caxias |
| http://dbpedia.org/resource/Adebayo_Lawal | http://dbpedia.org/resource/Offa_of_Mercia+                            |
| ...                                       | ...                                                                    |
+-------------------------------------------+------------------------------------------------------------------------+

Let's have a look at http://dbpedia.org/resource/Analía_Núñez :

DESCRIBE <http://dbpedia.org/resource/Analía_Núñez>

Among others, it returns the triples

dbr:Analía_Núñez  dbo:birthPlace    dbr:Panama ,
                                    dbr:David ,
                  <http://dbpedia.org/resource/David,_Chiriqu\u00ED> .

You can see three birth places. While it should be http://dbpedia.org/resource/David,_Chiriqu%C3%AD , you can see that something went wrong during the extraction from the infobox in the Wikipedia article about Analía Núñez .