  We analyze the ego-alter Twitter networks of 300 Italian MPs and 18 European
leaders, and of about 14,000 generic users. We find structural properties
typical of social environments, meaning that Twitter activity is controlled by
constraints that are similar to those shaping conventional social
relationships. However, the evolution of ego-alter ties is very dynamic, which
suggests that they are not entirely used for social interaction, but for public
signaling and self-promotion. From this standpoint, the behavior of EU leaders
is much more evident, while Italian MPs are in between them and generic users.
We find that politicians, more than generic users, create relationships as a
side effect of tweeting on discussion topics, rather than by contacting
specific alters.
