Riot is a type of Violence. Gun can be used for Violence. Gun is related to Tank. Tank is a different concept from Sleeve. 
Ecosystem is a type of Structure. Ecosystem is related to Desert. Desert is a type of Terrain. Terrain is related to Mountain. 
Riot --IsA--> Violence <--UsedFor-- Gun <--RelatedTo--> Tank <--DistinctFrom--> Sleeve 
Structure <--IsA-- Ecosystem <--RelatedTo--> Desert --IsA--> Terrain <--RelatedTo--> Mountain 