Frontier is a type of Boundary. you are likely to find Boundary in/at/on Basketball. you are likely to find Basketball in/at/on Closet. 
Proof is a type of Impression. Impression is related to Feel. Feel is related to Sensation. Sensation is created by Stimulus. 
Frontier --IsA--> Boundary --AtLocation--> Basketball --AtLocation--> Closet 
Proof --IsA--> Impression <--RelatedTo--> Feel <--RelatedTo--> Sensation --CreatedBy--> Stimulus 