{TAIL ~ The “cost} of survivability” is defined as {HEAD ~ the ratio} of the costs of network operation with and without survivability requirements 
{ TAIL ~ The “ cost } of survivability ” is defined as { HEAD ~ the ratio } of the costs of network operation with and without survivability requirements
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH