Character is a type of Recommendation. Character is related to Book. 
Flame is related to Smoke. Smoke is related to Artificial. Artificial is related to Equal. Equal is related to Comparable. 
Recommendation <--IsA-- Character <--RelatedTo--> Book 
Flame <--RelatedTo--> Smoke <--RelatedTo--> Artificial <--RelatedTo--> Equal <--RelatedTo--> Comparable 