A Few Dialogue Strategies - Man-Machine Dialogue: Design and Challenges - page 131

which characterizes a discourse or dialogue in which the instruction given by
the argumentative connectors is satisfied and any argumentative contradiction
is solved. All these aspects allow an MMD system to knowingly manage the
dialogue, that is to use a coherence and cohesion indicator and have additional
indications for its choice of answer, a process which we will now investigate.
8.1.5. Choosing an answer
When the user asks the system a question, the choice of answer is imposed
on it: either it knows the answer and gives it or it does not know the answer
and apologizes, tries to redirect the user on another path or, potentially, asks
the user to rephrase his/her question. In the context of a dialogue built over
several interventions, a question can involve much more complexity. Luzzati
[LUZ 95, p. 61] shows us that in the case of train ticket sales, it is common
for a human teller and thus a system to generate maximalist answers, that is
answers which systematically have more information than is required for
reasons of efficiency, especially to prevent potential follow-up questions. This
returns slightly to the emphatic repetition principle mentioned in section
8.1.2. Moreover, to better determine when the system can generate this type
of answer, which violates one of the Gricean maxims of quantity, it is helpful
to characterize the different types of possible question. Van Schooten et al.
[VAN 07] studied the importance of follow-up questions and were led to
suggest a question typology. Among the types of question, we have already
seen examples of closed questions, for which the possible answers are “yes”,
“no” and “I don't know”, and examples of open questions, for which the
answer is a propositional value such as a referring expression, a quantity or a
named entity, but we have not yet met questions such as “how can I make a
reservation?”. However, this question requires an explanation, which can be
hard for an MMD to carry out.
When the user gives the system an order, the choice of answers is also
imposed on it: at the same time as the system carries out the order, at least if
all the conditions are fulfilled (see section 6.2.1), it can generate an utterance
which on the one hand announces the action being carried out (especially if it
is invisible) and on the other hand allows the user to follow-up and continue
the natural dialogue. Following the order “reserve a first-class ticket for Paris
tomorrow morning”, a system's utterances such as “OK” or “done” are
probably not sufficient, because it closes the dialogue. An utterance including
a revival is more relevant, such as “it's done, would you like another