Edge is related to Surface. Surface is related to Chair. Chair is a synonym of Moderate. 
you are likely to find Darkness in/at/on Bed. you are likely to find Magazine in/at/on Bed. Resident is a type of Magazine. Resident is a type of Doctor. 
Edge <--RelatedTo--> Surface <--RelatedTo--> Chair <--Synonym--> Moderate 
Darkness --AtLocation--> Bed <--AtLocation-- Magazine <--IsA-- Resident --IsA--> Doctor 