Southwest is a type of Direction. Southwest is similar to Northwest. Northwest is a type of Location. Location is related to Dock. 
you would Work because Useful. you are likely to find Worker in/at/on Work. Scientist is a type of Worker. Theory is created by Scientist. 
Direction <--IsA-- Southwest <--SimilarTo--> Northwest --IsA--> Location <--RelatedTo--> Dock 
Useful <--MotivatedByGoal-- Work <--AtLocation-- Worker <--IsA-- Scientist <--CreatedBy-- Theory 