Question: Count the number of software which runs on Microsoft Windows and mac OS ?
SPARQL:
 SELECT DISTINCT COUNT(?uri) WHERE { ?uri <http://dbpedia.org/ontology/operatingSystem> <http://dbpedia.org/resource/Microsoft_Windows> . ?uri <http://dbpedia.org/ontology/operatingSystem> <http://dbpedia.org/resource/Mac_OS>}