Question: Give me all female German chancellors.
SPARQL:
PREFIX yago: <http://dbpedia.org/class/yago/>
PREFIX dbp: <http://dbpedia.org/property/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?uri ?string 
WHERE {
	?uri rdf:type yago:FemaleHeadsOfGovernment.
        ?uri dbp:office res:Chancellor_of_Germany .
        OPTIONAL { ?uri rdfs:label ?string . FILTER (lang(?string) = 'en') }
}