IEEE TRANS. ON AUDIO, SPEECH & LANGUAGE PROCESSING, VOL. ???, NO. ???, MONTH??? YEAR??? 1 Scaling POMDPs for spoken dialog management Abstract— Control in spoken dialog systems is challenging largely because automatic speech recognition is unreliable and hence the state of the conversation can never be known with cer- tainty. Partially observable Markov decision processes (POMDPs) provide a princi