A human Dialogue is a human to human interaction. turn each contributino to a conversation is called a “turn”, which contains a sentence, multiple sentences, or a single word turn-taking when to take the floor who takes the floor what happens during interruptions? barge-in barge-in is the property to allow the user to interrupt the system end-pointing deciding when a human has stopped talking, compute, etc. speech-act each turn is actually an “action” performed by the user constatives: committing the speaker to something being the case (answering, denying) directives: ask the addressee to do something (advising, ordering) com missives: commuting the speaker to future action (planning, voving) acknowledgement: reflecting the speaker’s attitude for something (apologizing, greeting, etc.) common ground grounding is the problem of acknowledging and reflecting the state of interaction; such as the elevator lighting up when pressed. acknowledgements and repeats is a way of grounding. we need to make sure that the system acknowledges user interaction adjacency pairs question => answer proposal => acceptance/rejection complements => downplay two-pair composition maybe interrupted or separated by a sub-dialogue conversational initiative Sometimes, such as during interviews, only one agent has initiative. This is not true most of the time during human-human interactions. mixed initiative is hard to achieve, usually we make dialogue systems as passive environments—only user and system understanding.