Question: When is the {marriage} of {significant event} forf {Franz Joseph I of Austria}?
Paraphrase: When is the {marriage} of {noteworthy occasion} forf {Franz Joseph I of Austria}?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q51056 wdt:P793 ?obj . ?obj wdt:P31 wd:Q8445 } 
Answer: Marriage of Franz Joseph I of Austria and Elisabeth of Bavaria