Principle is a synonym of Rule. Protocol is a type of Rule. Protocol is a synonym of Treaty. 
Bitter is a type of Taste. Taste is related to Type. one thing you do when you Program is Type. 
Principle <--Synonym--> Rule <--IsA-- Protocol <--Synonym--> Treaty 
Bitter --IsA--> Taste <--RelatedTo--> Type <--HasSubevent-- Program 