Dead is a different concept from Survivor. Casualty is a type of Survivor. Casualty is a type of Decrease. Decrease is a synonym of Contract. 
Light is related to Switch. Switch is related to Exchange. 
Dead <--DistinctFrom--> Survivor <--IsA-- Casualty --IsA--> Decrease <--Synonym--> Contract 
Light <--RelatedTo--> Switch <--RelatedTo--> Exchange 