Reference Resolution - Man-Machine Dialogue: Design and Challenges - page 104

station, as we saw in section 3.2.1. It can also try to deduce the missing
parameters by referring to the dialogue history (if a departure station was
mentioned at any time, it is a relevant candidate), to the situational context
(the departure station matches the location of the terminal used for the
dialogue) or to common sense (someone trying to buy a train ticket might
want to leave immediately, and this is a choice that the system can suggest
before asking the next question).
As always when it comes to language, ambiguities can occur and
complicate the reference resolution. In a system such as SHRDLU, this is the
case when we want to put one object on another or slot one in the other: an
utterance referring to an action requiring two objects as parameters can lead
to two interpretations, the correct interpretation and the interpretation in
which the objects are switched around. To decide, an analysis of the
prepositions used and the thematic roles is essential. More complicated is the
utterance such as “reserve a train ticket for Paris immediately”: does it mean
as soon as possible (on the next train) or does the “immediately” complement
only refer to the reservation order? A sentence can have optional
complements in the verbal valency meaning, as well as intermediate elements,
which cannot be predicted with the verb used but only by looking at its
hypernyms, unnecessary elements, which cannot be predicted with the verb
since they match adjunct adverbials or extra-peripheral elements such as
logical or discursive modifiers, e.g. “you know”. One of the MMD's tasks is
to use these linguistic elements to better manage the running conditions and
parameters of the application functions. Beyond the linguistic aspects, it also
happens that the action reference resolution involves purely applicative
aspects. If we consider, for example, that the task is implementing an object
deletion function, which only works with one parameter, thus a unique object,
then the utterances such as “delete these objects” lead either to an error
message (I need a single object. Which one shall I delete?) ortothe
implementation of a chain of executions of the deletion function. The last
solution is not necessarily relevant, for example if the deletion leads to
consequences for the other objects.
To solve such examples, reference resolution can involve a temporal
model. The goal is to take into account the temporal constraints involved in
the running of a function, which allow the system to very accurately model
chain actions, as well as the interactions between carrying out the actions and
the parallel evolution of the world of objects. With the train ticket reservation
example, such a temporal model is all the more necessary if there are several