2.2.2 Grounding Extension 1

Add a backward-transition from every state where input is expected.

An obvious solution for modeling grounding would be to add a backward-transition from every state where input is expected, pointing to the state before it, where the corresponding question is to be produced. This new edge should then be taken when the input given by the user is not understood. Here's the general picture:

Adding a transition

The resulting dialogue would be as follows:

This is a likely result, as the user cannot know why the failure to recognise the input occurred in the first place.