you are likely to find Bathroom in/at/on Flat. Bathroom is derived from Room. Room is related to Living. Living can cause/lead to Death. 
Mouse is a type of Animal. you are likely to find Liver in/at/on Animal. 
Flat <--AtLocation-- Bathroom --DerivedFrom--> Room <--RelatedTo--> Living --Causes--> Death 
Mouse --IsA--> Animal <--AtLocation-- Liver 