27. The system of claim 26 , wherein to accumulate the short-term shared knowledge about the current conversation, the one or more processors are further configured to expire the information about the utterance from the short-term context stack after a psychologically appropriate amount of time.
28. The system of claim 27 , wherein to accumulate the long-term shared knowledge about the user, the one or more processors are further configured to update one or more long-term profiles associated with the user to include information about the utterance received during the current conversation and relevant data associated with the information expired from the short term context stack.