Slope is a different concept from Top. Top is related to Point. Point is related to Indication. Symptom is a type of Indication. 
Preference is a type of Option. Option is a different concept from Must. Must is related to Ought. 
Slope <--DistinctFrom--> Top <--RelatedTo--> Point <--RelatedTo--> Indication <--IsA-- Symptom 
Preference --IsA--> Option <--DistinctFrom--> Must <--RelatedTo--> Ought 