Speech Acts of Assertion in Cooperative Informational Dialogue

SPEECH ACTS OF ASSERTION IN COOPERATIVE INYORMATIONAL DIALOGUE I.S. Kononenko AI Laboratory, Computer Center Siberian Division of the USSR Ac. Sci. Novoslblrsk 630090,USSR ABSTRACT Dialogue systems should provide a cooperative informational dialogue aimed at knowledge sharing . In the paper speech acts of assertion (SAA) are assumed to be the means of achieving this goal. A typology of SAAs is proposed which reflects certain cognitive aspects of communicative situation at different stages of mutual informing process. Infor- mation constituents of the type assertions are for- mally described to represent a current cognitive state of the speaker's knowledge base, each proposi- tion in it being characterized by a subjective veri-- similitude evaluation. The general scheme of infor- mation flow in the cooperative dialogue is consi- dered. With regard to this scheme the dialogue func- tions of SAAs are discussed. I.INTRODUCTION We must strive to provide dialogue systems with ability to interact with tile user in the kind of cooperative human-like dialogues of informa- tional type. By this type of a dialogue we mean a mutual informing a c t i v i t y of interaction partici- pants -- similar to Car]son's (1984) dialogue game of information sharing - aimed at enriching the stock g of shared (mutually coordinated) knowledge. Our tenet in this study is that SAAs are performed in dialogues to approach the general goal of shared knowledge. The proposed typology of SAAs reflects their dialogue functions and contribution into the information flow process. Performing an SAA the speaker X conveys to the addressee Z the information about some actual situa- tion S, i . e . about some part of the 'world' which a topic of the dialogue refers to. It is assumed here that appropriateness of the SAA is determined by conditions formulated in terms of contextual proper- ties of the current communicative situation inclu- ding knowledge, beliefs, evaluations and goals of interaction participants (van Dijk, 1984). Certain cognitive aspects of eommunicatlve situation are considered to be a necessary precondition for SAA performance and simultaneously a part of SAA integ- ral content. To simulate the cognitive situation and repre- sent information constituents of SAA content in a participant's (for example, X's) knowledge base two cognitive components are defined. Let X be a set of utterances {P} whleh represents a current cognitive state of X (denoted as X:P). A cognitive component X:Z is distinguished in X which is a reflection of in X (X's beliefs about Z's knowledge including Z's beliefs about his partner X's state of knowledge), i.e. a set of utterances of the form P=Z:P'. Then tile rest of X is X's own knowledge about the world. Now M may be defined as a set of utterances simul- taneously contained in X, Z, X:Z and Z:X ( a weak definition of M). 2. COGNITIVE ASPECTS OF COMMUNICATIVE SITUATION Tile nucleous of integral content of tile SAA is a propositional structure, in the simplest case, a proposition P which represents S in a generalized and semantically structured …

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