Half is related to Percentage. Percentage is related to Sale. Sale is related to Discount. 
Abstract is a type of Consider. Abstract is related to Sight. Sight is the opposite of Smell. 
Half <--RelatedTo--> Percentage <--RelatedTo--> Sale <--RelatedTo--> Discount 
Consider <--IsA-- Abstract <--RelatedTo--> Sight <--Antonym--> Smell 