1. A method comprising: at a turn in a dialog between a user and a spoken dialog system: nominating, via a processor configured to perform speech recognition, a set of dialog actions and a set of contextual features, wherein the processor uses a partially observable Markov decision process in parallel with a conventional dialog state to perform the nominating; and generating an audible response in the dialog based on the set of contextual features, via a machine learning algorithm, from the set of dialog actions.