Vary is a type of Differ. Differ is a synonym of Disagree. Argue entails/necessarily involves Disagree. Defend is a type of Argue. 
Slope is related to Action. Action is related to Control. Dominate is a type of Control. Dominate is the opposite of Submit. 
Vary --IsA--> Differ <--Synonym--> Disagree <--Entails-- Argue <--IsA-- Defend 
Slope <--RelatedTo--> Action <--RelatedTo--> Control <--IsA-- Dominate <--Antonym--> Submit 