Enforce is a synonym of Implement. Implement is related to Pencil. 
Class is related to Security. Peace is a type of Security. Peace is related to Earth. Earth is related to Salt. 
Enforce <--Synonym--> Implement <--RelatedTo--> Pencil 
Class <--RelatedTo--> Security <--IsA-- Peace <--RelatedTo--> Earth <--RelatedTo--> Salt 