Gap is a type of Opening. Opening is related to Introduction. Introduction is derived from Introduce. Introduce is related to Stranger. 
Protest is related to Violent. Violent is related to Attack. Attack is related to Kill. Stone is a type of Kill. 
Gap --IsA--> Opening <--RelatedTo--> Introduction --DerivedFrom--> Introduce <--RelatedTo--> Stranger 
Protest <--RelatedTo--> Violent <--RelatedTo--> Attack <--RelatedTo--> Kill <--IsA-- Stone 