Question: Which U.S. states possess gold minerals?
SPARQL query:
PREFIX yago: <http://dbpedia.org/class/yago/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX prop: <http://dbpedia.org/property/>
SELECT DISTINCT ?uri ?string
WHERE 
{
        ?uri rdf:type yago:StatesOfTheUnitedStates .
        ?uri prop:mineral ?mineral .
        FILTER (regex(?mineral,'Gold')) .
        OPTIONAL {?uri rdfs:label ?string. FILTER (lang(?string) = 'en') }
}