PED is a dialogue management system that uses a
probabilistic nested belief model to choose
dialogue strategies. The dialogue system designer
need only supply a set of plan rules to PED as a
dialogue grammar with preconditions. Using this
grammar, PED constructs game trees (like the one
below) to represent the outcomes of the dialogue,
so that a dialogue strategy can be chosen for the
current turn in the dialogue. PED automatically
maintains a belief model by a belief revision
process that uses the observed acts in the
dialogue. The game tree is evaluated in the
context of this belief model. PED is efficient
because it uses probabilistic estimates of belief
rather than a plain logical belief model.
