Arrow is related to Line. Boundary is a type of Line. Boundary is related to District. District is related to Market. 
Fleet is part of Airline. Song is a type of Airline. Song is related to Composition. Composition is a type of Essay. 
Arrow <--RelatedTo--> Line <--IsA-- Boundary <--RelatedTo--> District <--RelatedTo--> Market 
Fleet --PartOf--> Airline <--IsA-- Song <--RelatedTo--> Composition --IsA--> Essay 