public int compareTo(ReinforcementKey rk2) {
    	ReinforcementKey rk1 = this;
    	
    	if( rk1.x < rk2.x ){
    		return -1;
    	}else if( rk1.x > rk2.x ){
    		return 1;
    	}else if( rk1.y < rk2.y ){
    		return -1;
    	}else if( rk1.y > rk2.y ){
    		return 1;
    	}else if( rk1.z < rk2.z ){
    		return -1;
    	}else if( rk1.z > rk2.z ){
    		return 1;
    	}else{
    		return rk1.world.compareTo(rk2.world);
    	}
    }