In {TAIL ~ addition}, {HEAD ~ links} can be added to the network topology model to reduce the cost of network operation 
In
In { TAIL ~ addition } , { HEAD ~ links } can be added to the network topology model to reduce the cost of network operation
REL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH