Last is related to Position. Position is related to Center. Seat is a type of Center. 
Exchange is related to Price. Price is related to Oil. Oil is related to Potential. Potential is the opposite of Real. 
Last <--RelatedTo--> Position <--RelatedTo--> Center <--IsA-- Seat 
Exchange <--RelatedTo--> Price <--RelatedTo--> Oil <--RelatedTo--> Potential <--Antonym--> Real 