What is {spouse} of {Buster Keaton} that is {start time} is {1921-5-31} ?
On May 31, 1921, who wed Buster Keaton?
Who did Buster Keaton marry on May 31, 1921?
SELECT ?r WHERE { resource:Buster_Keaton property:spouse ?n . FILTER ( CONTAINS ( YEAR ( ?z ) , '1921' ) ) . ?n property:start_time ?z . ?n property:spouse ?r }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q103949> .
?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> ?obj .
?statement <http://www.wikidata.org/entity/P580> <1921-5-31>
} 

SELECT ?obj WHERE { wd:Q103949 p:P26 ?s . ?s ps:P26 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1921')) }