{TAIL ~ A server} receives an interaction history comprising a set of one to {HEAD ~ one interactions} between a first user and other users 
{ TAIL ~ A server } receives an interaction history comprising a set of one to { HEAD ~ one interactions } between a first user and other users
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH