Question: Which nation's engineers have graduated in Poland?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE { ?x onto:education <http://dbpedia.org/resource/Poland> . ?x prop:nationality ?uri . ?x rdf:type onto:Engineer}