Question: Which appointer of William Clark is the successor of Levi Lincoln Sr ?
SPARQL:
 SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Levi_Lincoln,_Sr.> <http://dbpedia.org/property/successor> ?uri. <http://dbpedia.org/resource/William_Clark> <http://dbpedia.org/property/appointer> ?uri}