Viewer is derived from View. View is related to Eye. Eye is related to Pair. Pair is related to Group. 
Expense is related to Account. Account is a synonym of Calculate. Calculate is a type of Judge. Assign is a type of Judge. 
Viewer --DerivedFrom--> View <--RelatedTo--> Eye <--RelatedTo--> Pair <--RelatedTo--> Group 
Expense <--RelatedTo--> Account <--Synonym--> Calculate --IsA--> Judge <--IsA-- Assign 