Sphere is related to Eye. Eye is the opposite of Ear. 
Symbol is related to Liberty. Liberty is related to Concept. Hypothesis is a type of Concept. Hypothesis is the opposite of Fact. 
Sphere <--RelatedTo--> Eye <--Antonym--> Ear 
Symbol <--RelatedTo--> Liberty <--RelatedTo--> Concept <--IsA-- Hypothesis <--Antonym--> Fact 