The Hidden Information State Approach to Dialog Management

The Hidden Information State model: A practical framework for POMDP-based spoken dialogue management

“…The most common acts are listed in Table 1 and a simple dialogue illustrating their use is shown in Table 2. A full description of the dialogue act set used by the HIS system is given in Young (2007).…”

“…The system typically maintains a distribution of upto several hundred partitions corresponding to many thousands of dialogue states. The HIS system has been described in outline in a number of conference papers (Young, 2006;Young et al, 2007;. The aim of this paper is to provide a single coherent and more detailed description of how the HIS system works, and an assessment of its performance characteristics.…”

Bayesian update of dialogue state for robust dialogue systems

“…This prior information is included in the learning process by grouping such actions together. The groups are called summary actions and play a similar role to the summary actions of the HIS model [3]. Typical summary actions will be to "request", "confirm" the most likely value or to "select" between the top two values for a particular slot.…”

“…This number grows exponentially with the number of slots in the system. In the Hidden Information State model, learning was implemented by summarising the full belief distribution according to the beliefs in the most likely partitions [3]. An algorithm for online learning of the Q function was then implemented using a grid-based approximation.…”

“…This led to the Hidden Information State (HIS) model being suggested as a less computationally demanding approach [3]. The HIS model improves efficiency by grouping together user goals into partitions which are indistinguishable given the past user utterances.…”