what is the {start time} for {Iannis Xenakis} has {spouse} as {Françoise Xenakis} ?
When did Iannis and Francoise Xenakis wed?
When did Iannis Xenakis marry Francoise Xenakis?
SELECT ?n WHERE { resource:Iannis_Xenakis property:spouse ?x . ?x property:start_time ?n . ?x property:spouse resource:Françoise_Xenakis }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q152880> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P26> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q3086635> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q152880 p:P26 ?s . ?s ps:P26 wd:Q3086635 . ?s pq:P580 ?value}