Sleep is related to State. Articulate is a type of State. 
Elbow is related to Middle. Middle is related to Class. Class is related to Literature. Literature is related to Form. 
Sleep <--RelatedTo--> State <--IsA-- Articulate 
Elbow <--RelatedTo--> Middle <--RelatedTo--> Class <--RelatedTo--> Literature <--RelatedTo--> Form 