distribution of social contents has shifted
from a “central-edge” manner to an “edgeedge”
manner. Eytan Bakshy and his colleagues
studied the social influence of people in the
online social network, observing that some
users can be very influential in social propagation.
33 Haitao Li, Haiyang Wang, and Jiangchuan
Liu studied the content sharing in an
online social network and observed the skewed
popularity distribution of content and the
power-law activity of users.34 Giovanni Comarela
and his colleagues investigated response
time of social contents using collected traces
and observed factors that affect the response
time in social propagation.