what is the {end time} for {Alan Greenspan} has {position held} as {Chair of the Federal Reserve} ?
Alan Greenspan left his position as Chair of the Federal Reserve on what date?
When did Alan Greenspan leave his position as Chair of the Federal Reserve?
SELECT ?z WHERE { ?s property:end_time ?z . resource:Alan_Greenspan property:position_held ?s . ?s property:position_held resource:Chair_of_the_Federal_Reserve }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q193635> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q2666591> .
?statement <http://www.wikidata.org/entity/P582> ?value. 
} 

SELECT ?value WHERE { wd:Q193635 p:P39 ?s . ?s ps:P39 wd:Q2666591 . ?s pq:P582 ?value}