Fix is a type of Establish. Establish is a synonym of Determine. Charge is a type of Determine. 
Enforce is a synonym of Implement. Implement is related to Pencil. you are likely to find Pencil in/at/on University. you are likely to find Book in/at/on University. 
Fix --IsA--> Establish <--Synonym--> Determine <--IsA-- Charge 
Enforce <--Synonym--> Implement <--RelatedTo--> Pencil --AtLocation--> University <--AtLocation-- Book 