Middle is related to Exact. Exact is the opposite of Loose. Loose is a synonym of Separate. Separate is the opposite of Join. 
Singer is related to Stage. Platform is a type of Stage. Platform is related to Board. Board is related to Area. 
Middle <--RelatedTo--> Exact <--Antonym--> Loose <--Synonym--> Separate <--Antonym--> Join 
Singer <--RelatedTo--> Stage <--IsA-- Platform <--RelatedTo--> Board <--RelatedTo--> Area 