Question: Was the Cuban Missile Crisis earlier than the Bay of Pigs Invasion?
SPARQL query:
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX res: <http://dbpedia.org/resource/>
ASK WHERE 
{
        res:Cuban_Missile_Crisis onto:date ?x .
	res:Bay_of_Pigs_Invasion onto:date ?y .
	FILTER (?x < ?y)
}