code: private boolean compareRelation(RCCConstraint first,
  			RCCConstraint second) {
  		
  		boolean existed = false;
  		for (int i = 0; i < first.types.length; i++) {
  			existed = false;
  			for (int j = 0; j < second.types.length; j++) {
  				if(first.types[i] == second.types[j])
  					existed = true;
  			}
  			if(!existed) return false;
  		}
  		
  		return true;
  	}
docs: return true when they are equal