the survivability characteristics of the modified network has deteriorated in {HEAD ~ comparison} to {TAIL ~ the survivability characteristics} of the current network topology; and 
to
the survivability characteristics of the modified network has deteriorated in { HEAD ~ comparison } to { TAIL ~ the survivability characteristics } of the current network topology ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH