From speech recognition to speech understanding : A case study of Keal

We describe in this paper the comprehension part of a man-machine dialog system which performs automatic inquiry in a limited domain. The comprehension part involves a semantic interpreter and a dialog manager. The extraction of the semantic information conveyed by a sentence is based on an interpretation of the parse-tree; the semantic knowledge is represented by transformation rules associated with the production rules of a semantic context-free grammar. The pragmatic model, which has been designed with respect to its recognition environment, is able to take into account some particularities of the oral conversation (ellipsis, unexpected information), in order to make the dialog as natural as possible. It also makes predictions about possible user´s replies to assist recognition and semantic interpretation.