  For maximizing influence spread in a social network, given a certain budget
on the number of seed nodes, we investigate the effects of selecting and
activating the seed nodes in multiple phases. In particular, we formulate an
appropriate objective function for two-phase influence maximization under the
independent cascade model, investigate its properties, and propose algorithms
for determining the seed nodes in the two phases. We also study the problem of
determining an optimal budget-split and delay between the two phases.
