what is the {start time} for {Duisburg} has {head of government} as {August Seeling} ?
On what date Duisburg started as head of government August Seeling?
When Duisburg started as head of government August Seeling?
SELECT ?f WHERE { resource:Duisburg property:head_of_government ?c . ?c property:start_time ?f . ?c property:head_of_government resource:August_Seeling }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q2100> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P6> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q763958> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q2100 p:P6 ?s . ?s ps:P6 wd:Q763958 . ?s pq:P580 ?value}