La requête :

PREFIX abo: <http://artemisBookstore.com/ontology#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>

SELECT (COUNT (distinct ?writer) AS ?nbWriters)
WHERE {
  ?writer a abo:Writer.
  FILTER NOT EXISTS { ?writer owl:sameAs ?uri }
} 

Le résultat est 502