Dialogue actions for natural language interfaces Arne Jonsson Department of Computer and Information Science Linkoping University S-581 83 LINKOPING, SWEDEN email arnjo@ida hu se Abstract This paper presents an action scheme for dia logue management for natural language inler faces The scheme guides a dialogue manager which directs the interface's dialogue with the user communicates with the background sys- tem, and assists the interpretation and gets eration modules The dialogue manager was designed on the basis of an investigation of empirical material collected in Wizard of Oz experiments The empirical investigations re vealed that in dialogues with database systems users specify an object, or a set of objects and ask for domain concept information, e g the value of a property of that object or set of ob|ects The interface responds 1 perform ing the appropriate action e g providing the requited information or initiating a clarified lion subdialogue The action to bt carried out by the interface can be determined based on how objects and properties are specified from information in the user utterance the dialogue context and the response from the background system and its domain model 1 Introduction Users of natural language interfaces, should conveniently be able to express the commands and queries that the background system can deal with and the system should react quickly and accurately to all user input Among other things this means that the interface must be able to cope with connected dialogue However, it does not mean that the interface must bt able to mimic human interaction On the contrary, it is erroneous to as- sume that humans would like to interact with cornput ers the same way as they communicate with humans (cf [Dahlback, 1991b 1991a, Dahlback and Jonsson, 1992 Dahlback et al, 1993, Krause, 1993]) Human computer interactions have their own sublanguages (cf [ G r i shman and Kittredge, 1986]) whose characteristics often allow a much simpler dialogue model than models capturing human interaction To illustrate some properties of such human computer interaction consider figure 1 In information retrieval systems a common user initiative is a request for do- main concept information of a specified object, or set of objects Utterance U11 illustrates this The requested domain concept information is the value of the property shape and the domain object is the Ford Fiesta costing 26 800 crowns Unfortunately the system could not an swer the question as the propert> (shapt) is not utilized in the domain, instead in utterance S12 the system pro- vides information about its capabilities In U13 a new request for information on another property of the same domain object is presented This time the pronoun it replaces the rephrasing of the specification of the object, ic the Ford Fiesta costing 26 800 crowns In utter- ance U15 the user asks for the same concept information but related to another object while in U17 the object stays the same but the property is altered In U19 the property remains the same but this time the user uti- lizes a definite description to specify an object discussed previously, and originally specified in utterance U11 The dialogue model presented in this paper does not intend to mimic human conversation It is based on the observation that for information retrieval applications a common user initiative is a request for domain concept information of a specified object or set of objects (cf [Ahrenberg 1987]) A dialogue manager utilizing this information when deciding winch action to perform for user natives concerned with accessing the application will provide efficient and robust user-friendly human computer natural language interaction 2 The Dialogue Manager A dialogue manager directs a natural language interface and holds information needed by the modules in the in- terface, including the dialogue manager itself The Di- alogue Manager considered in this paper was designed from an analysis of a corpus of 21 dialogues using live different background systems [Ahrenberg et al 1990, Jonsson 1991], collected in Wizard Oz-experiments [Dahlback et al 1993] The Dialogue Manager need to be customized to account for the sublanguage car- ried out in a specific application Customization al- lows us to adapt the behaviour of the interface to the requirements of the application (see Jonsson [1993a, 1993b] for details) The results presented here are based on the customiza- J0NSSON 1406