  Conversation between two people is usually of mixed-initiative, with control
over the conversation being transferred from one person to another. We apply a
set of rules for the transfer of control to 4 sets of dialogues consisting of a
total of 1862 turns. The application of the control rules lets us derive
domain-independent discourse structures. The derived structures indicate that
initiative plays a role in the structuring of discourse. In order to explore
the relationship of control and initiative to discourse processes like
centering, we analyze the distribution of four different classes of anaphora
for two data sets. This distribution indicates that some control segments are
hierarchically related to others. The analysis suggests that discourse
participants often mutually agree to a change of topic. We also compared
initiative in Task Oriented and Advice Giving dialogues and found that both
allocation of control and the manner in which control is transferred is
radically different for the two dialogue types. These differences can be
explained in terms of collaborative planning principles.
