what is the {start time} for {Ricardo Lagos} has {position held} as {President of Chile} ?
In which year Ricardo Lagos became the President of Chile?
When did Ricardo Lagos hold the position as President of Chile?
SELECT ?n WHERE { ?n property:position_held resource:President_of_Chile . ?n property:start_time ?n . resource:Ricardo_Lagos property:position_held ?n }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q331> .
?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/Q466956> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q331 p:P39 ?s . ?s ps:P39 wd:Q466956 . ?s pq:P580 ?value}