Belief revision

During the dialogue the belief state of the first agent changes due to belief revision. To illustrate the development of the belief state consider an example initial state. Notice that there are five levels since the game tree has a depth of 5.

level 1:
{
p(intend(ask-car-spanner),1)
}

level 2:
{
}

level 3:
{
p(intend(ask-car-spanner),0.7)
p(intend(ask-bike-spanner),0.3)
}

level 4:
{
}

level 5:
{
p(intend(ask-car-spanner),0.7)
p(intend(ask-bike-spanner),0.3)
}

Now consider the alternatives available in the game tree (figure 4.2). ask-ambiguous has no effect on the mental state since there are two alternative parent intentions to this act. On the other hand, there is only one parent available for ask-unambiguous and so agent 2 may revise its belief about agent 1's intention. This is an alternating mutual revision and so level 3 and level 5 are revised. The same effect is obtained by using the answer-car and answer-bike acts since these two have a single possible parent intention. The following is the resulting belief model:

level 1:
{
p(intend(ask-car-spanner),1)
}

level 2:
{
}

level 3:
{
p(intend(ask-car-spanner),1)
}

level 4:
{
}

level 5:
{
p(intend(ask-car-spanner),1)
}