Landmark-Based Location Belief Tracking in a Spoken Dialog System
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Many modern spoken dialog systems use probabilistic graphical models to update their belief over the concepts under discussion, increasing robustness in the face of noisy input. However, such models are ill-suited to probabilistic reasoning about spatial relationships between entities. In particular, a car navigation system that infers users? intended destination using nearby landmarks as descriptions must be able to use distance measures as a factor in inference. In this paper, we describe a belief tracking system for a location identification task that combines a semantic belief tracker for categorical concepts based on the DPOT framework (Raux and Ma, 2011) with a kernel density estimator that incorporates landmark evidence from multiple turns and landmark hypotheses, into a posterior probability over candidate locations. We evaluate our approach on a corpus of destination setting dialogs and show that it significantly outperforms a deterministic baseline.
