To model some of the interaction between the Giver and the Follower, we additionally consider in our model the previous dialog act of the Follower, which could for example be: Given point-set W and preceding Follower act f , as the giver, we need to determine a procedure for choosing which dialog act g and semantic unit u to produce.
we are interested in the following distribution: which says that, as the Giver, we select our utterances on the basis of what the Follower says, and on the set of waypoints we next wish to describe.