Frontier is a type of Wilderness. you are likely to find River in/at/on Wilderness. River is related to Natural. Natural is a synonym of Indigenous. 
Basis is a synonym of Base. Base is a different concept from Top. Top is related to Eye. 
Frontier --IsA--> Wilderness <--AtLocation-- River <--RelatedTo--> Natural <--Synonym--> Indigenous 
Basis <--Synonym--> Base <--DistinctFrom--> Top <--RelatedTo--> Eye 