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