Temporal Contexts for Discourse Representation: An Extension of the Conceptual Graph Approach

• Authors: Bernard Moulin
• Venue: Applied Intelligence
• Year: 1997

A discourse is composed of a sequence of sentences that must beinterpreted with respect to the context in which they are uttered andto the actions that produce them: locutors‘ speech acts. The analysisof discourse content must be based on a pragmatic approach to thestudy of language in use. Some of the most obvious linguisticelements that require contextual information for their representationare deictic forms such as here, now, I, you, this, andverb tenses.Several authors have recognized a need for introducing contextualstructures in knowledge representation models such as semanticnetworks. Sowa‘s Conceptual Graph Theory is apowerful approach to conceptually represent knowledge contained indiscourses. However, it must be extended in order to represent several semantic andpragmatic mechanisms related to the expression of time in naturallanguage. In this paper we present such an extension as a frameworkfor modeling temporal knowledge in discourses integrating severalfeatures borrowed from speech act theory.First, we introduce the notions of time interval, temporal object,temporal situation, and temporal relation. Then, we discuss theimportance of explicitly introducing the concept of time coordinatesystem in a discourse representation and we present different kindsof temporal contexts: narrator‘s perspective, agent‘s perspective andtemporal localization. We show how this conceptual framework can beused to represent various referential mechanisms in discourse such asanaphoras, indexicals, direct and indirect styles. We also discusshow to model several linguistic phenomena such as speech actcharacteristics and the specification of performative and attitudeutterances. Finally, we briefly discuss how verb tenses can bedetermined in a discourse on the basis of this temporal approach.