Scaling POMDPs for Dialog Management with Composite Summary Point-Based Value Iteration (CSPBVI)

Jason D. Williams, Steve Young

Although partially observable Markov decision processes (POMDPs) have shown great promise as a framework for dialog management in spoken dialog systems, important scalability issues remain. This paper tackles the problem of scaling slot-filling POMDP-based dialog managers to many slots with a novel technique called composite point-based value iteration (CSPBVI). CSPBVI creates a local POMDP policy for each slot; at runtime, each slot nominates an action and a heuristic chooses which action to take. Experiments in dialog simulation show that CSPBVI successfully scales POMDP-based dialog managers without compromising performance gains over baseline techniques and preserving robustness to errors in user model estimation.

Subjects: 15.5 Decision Theory; 1.11 Planning

Submitted: May 9, 2006

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