8. A system comprising: a processor; and a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising: at each turn in a dialog nominating, using a partially observable Markov decision process in parallel with a conventional dialog state, a set of allowed dialog actions and a set of contextual features; and generating a response based on the set of contextual features and a dialog action selected, via a machine learning algorithm, from the set of allowed dialog actions.
8. A system comprising: a processor; and a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising: at each turn in a dialog nominating, using a partially observable Markov decision process in parallel with a conventional dialog state, a set of allowed dialog actions and a set of contextual features; and generating a response based on the set of contextual features and a dialog action selected, via a machine learning algorithm, from the set of allowed dialog actions. 9. The system of claim 8 , the computer-readable storage medium having additional instructions stored which result in operations comprising using reinforcement learning to augment the machine learning algorithm.