Edge is related to Cliff. Cliff is related to Steep. Steep is related to Hill. Hill is related to Formation. 
Disaster is a type of Destruction. Disaster is related to Tragedy. Tragedy is a type of Drama. 
Edge <--RelatedTo--> Cliff <--RelatedTo--> Steep <--RelatedTo--> Hill <--RelatedTo--> Formation 
Destruction <--IsA-- Disaster <--RelatedTo--> Tragedy --IsA--> Drama 