“…The role of the leader is not fixed, and it may change during the course of the dialogue when a new member joins the group, or when the current leader leaves the dialogue. Therefore PISA uses a token-based technique to identify the group's leader, similar to that of Ambroszkiewicz, Matyja, and Penczek (1998) where the token is used as a sign of decision power among a team of software agents.…”