Efficiency is a type of Ratio. Ratio is similar to Proportion. Content is a type of Proportion. Issue is a type of Content. 
Anger is etymologically related to Ugly. Anger is the opposite of Happiness. Cheer can cause/lead to Happiness. 
Efficiency --IsA--> Ratio <--SimilarTo--> Proportion <--IsA-- Content <--IsA-- Issue 
Ugly <--EtymologicallyRelatedTo-- Anger <--Antonym--> Happiness <--Causes-- Cheer 