Stone is related to Stick. Stick is related to Degree. Degree is related to Calculation. 
Exchange is related to Market. you are likely to find Merchant in/at/on Market. Merchant is a synonym of Vendor. Vendor is a synonym of Seller. 
Stone <--RelatedTo--> Stick <--RelatedTo--> Degree <--RelatedTo--> Calculation 
Exchange <--RelatedTo--> Market <--AtLocation-- Merchant <--Synonym--> Vendor <--Synonym--> Seller 