Invention is created by Imagination. Invention is a synonym of Innovation. 
Nation is the opposite of City. you are likely to find Factory in/at/on City. Factory is related to Working. Working is related to Duty. 
Imagination <--CreatedBy-- Invention <--Synonym--> Innovation 
Nation <--Antonym--> City <--AtLocation-- Factory <--RelatedTo--> Working <--RelatedTo--> Duty 