{HEAD ~ the network} cost for operating the modified network topology is greater than or equal to {TAIL ~ the network cost} for operating the current network topology 
{ HEAD ~ the network } cost for operating the modified network topology is greater than or equal to { TAIL ~ the network cost } for operating the current network topology
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH