Question: What is the { chairperson } of the { International Mathematical Union } that is { end time } { 1978 - 0 - 0 }?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q828490 p:P488 ?s . ?s ps:P488 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'1978')) }