Construct Algebra: Analytical Dialog Management

Construct Algebra: Analytical Dialog Management Alicia Abella and Allen L. Gorin AT cT Labs Research 180 Park Ave. Bldg 103 Florham Park, NJ 07932 Abstract In this paper we describe a systematic approach for creating a dialog management system based on a Construct Algebra, a collection of relations and operations on a task representation. These relations and operations are analytical components for building higher level abstractions called dialog motivators. The dialog manager, con- sisting of a collection of dialog motivators, is entirely built using the Construct Algebra. 1 INTRODUCTION The dialog manager described in this paper implements a novel approach to the problem of dialog management. There are three ma- jor contributions: the task knowledge repre- sentation, a Construct Algebra and a collec- tion of dialog motivators. The task knowl- edge representation exploits object-oriented paradigms. The dialog motivators provide the dialog manager with the dialog strate- gies that govern its behavior. The Construct Algebra provides the building blocks needed to create new dialog motivators and analyze them. The first main component of this dialog manager is the task knowledge representa- tion. The task knowledge is encoded in ob- jects. These objects form an inheritance hi- erarchy that defines the relationships that exists among these objects. The dialog man- ager exploits this inheritance hierarchy in de- termining what queries to pose to the user. No explicit states and transitions need to be defined using this framework (Bennacef et al., 1996; Meng and et. al., 1996; Sadek et al., 1996). A change to the dialog does not require a change to the dialog manager, but more simply, a change to the inheritance hi- erarchy. The second main component of this dia- log manager is the collection of dialog mo- tivators. The dialog motivators determine what actions need to be taken (e.g. ask a confirmation question). The dialog motiva- tors are founded on a theoretical framework called a Construct Algebra. The Construct Algebra allows a designer to add new moti- vators in a principled way. Creating a new application requires defining the inheritance hierarchy and perhaps additional dialog mo- tivators not encompassed in the existing col- lection. This dialog manager has been used for two applications. The first is a spoken dialog sys- tem that enables a user to respond to the open-ended prompt How may I help you? (HMIHY) (Gorin et al., 1997). The sys- tem recognizes the words the customer has said (Riccardi and Bangalore, 1998) and ex- tracts the meaning of these words (Wright et al., 1998) to determine what service they want, conducting a dialog (Abella and Gorin, 1997; Abella et al., 1996) to effec- tively engage the customer in a conversa- tion that will result in providing the service they requested. The second application is to Voice Post Query (VPQ) (Buntschuh et al., 1998) which provides spoken access to the information in large personnel database (> 120,000 entries). A user can ask for em- ployee information such as phone number, fax number, work location, or ask to call …

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