Generating Dialogue
Naoyuki OKADA
Department of Artificial Intelligence,
Kyushu Institute of Technology
Iizuka 820, Japan
e-mail: okada@pluto.ai.kyutech.ac.jp
The three items on the discourse structure of dialogue in "invitation"
are discussed: dialogue environment, invitation structure, and
dialogue process.
First, the environment of dialogue is shown. An intelligent agent
simulating the protagonist of an Aesop fable was constructed
previously. The agent (k-system) has desires, makes plans to satisfy
them, recognizes its surroundings, takes action to execute the plans,
gets emotional and utters those processes in natural language. Based
on this, another agent (p-system) is constructed: first, a copy of
k-system was made. Then high-level concepts are kept as they are, but
low-level concepts or instances are changed to special one to the
p-system. The parameters of physiological and emotional states are
also changed. Thus, the p-system can be completed to have a
conversation with the p-system.
The dialogue is as follows: the k-system tries to go to a mansion,
find a pond in the garden, and drinks water, because he is thirsty
very much. On the way to the mansion, he meets the p-system, and
exchanges greetings. He knows the mansion is very dangerous now, and
hesitates to proceed with the original plan further. The p-system
reads his mind, and to invite him to change the plan and come to the
river side at a bridge together with the p-system. Although the river
side is a little bit far, he finally agrees to the p-system.
Next, the discourse structure of invitation is represented by
networks. More than thirty examples of invitation dialogues are
investigated in detail, and a representation scheme is proposed. It
consists of two kinds of mental models: inviting and invited sides.
Each model has two layers of networks: rough and detailed. The rough
model of inviting side has two components: the goal explanation part
and the persuasion/negotiation part. Depending on the opponent's
response to the goal explanation, the persuasion/negotiation part
chooses several strategies: to make opponent's another plan give up,
to compromise with each other on time or location in executing the
one's plan, to show the merits/demerits of one's/opponent's plan,
and so on. On the other hand, the invited model has corresponding
components to the inviting ones: the explanation comprehension part
and the assertion/negotiation part.
The p-system, which tries to invite the k-system to do something,
contains both the inviting model to achieve an invitation and the
invited model to read the opponent mind. The k-system contains both
models, too, but their roles of "main and sub-" interchange each
other.
Third, the process of an invitation dialogue is analyzed according to
the networks. Although the representation roughly indicates the
transition of mental states of each side, it is a kind of "default
value" of various transitions. The models are designed to
well-manipulate such a transition. In particular, the complicated
transition of the inviting model of the p-system is shown in detail as
the dialogue proceeds. Thus, the models can be expected to be robust
in various dialogues.
Finally, our summary is given: the discourse structure of invitation
is made clear. Not only the inviting model but the invited one are
represented by two-layer networks. The networks can interpret various
invitations through flexible transitions.
Keywords: dialogue generation, discourse structure, mental process, invitation