Did {Martin_Luther} {child} {Magdalena Luther}?
Did Magdalena Luther have a son named Martin Luther?
Is Martin Luther a son of Magdalena Luther?
ASK WHERE { resource:Martin_Luther property:child resource:Magdalena_Luther }
 ASK { ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q9554> . ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P40> . ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q6729875>. } 
ASK WHERE { wd:Q9554 wdt:P40 wd:Q6729875 }