Task is related to Project. Project is related to Case. Case is related to Airplane. Fighter is a type of Airplane. 
Fence is a type of Border. Border is related to Country. Country is related to Category. Category is related to Art. 
Task <--RelatedTo--> Project <--RelatedTo--> Case <--RelatedTo--> Airplane <--IsA-- Fighter 
Fence --IsA--> Border <--RelatedTo--> Country <--RelatedTo--> Category <--RelatedTo--> Art 