Did {Warren_Buffett} {family name} {Buffett}?
Did Warren Buffett have Buffett as family name?
was warren buffett's family name buffett?
ASK WHERE { resource:Warren_Buffett property:family_name resource:Buffett }
 ASK { ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q47213> . ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P734> . ?statement1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q21492748>. } 
ASK WHERE { wd:Q47213 wdt:P734 wd:Q21492748 }