Forward And Backward Reasoning In Automatic Abstracting

bounded scope dialogue with the user in order to collect his suggestions about the structure and content of the texts to be su~mmrized, and his requirements on the summary to be generated. This information is embedded in two different frameworks called working_ text schema and working summmar~, schema which contain the user's suggestions and requirements, respectively. The schemas will constitute a fundamental input for the following phases of the system operation. The working schemas are defined by the user. under the continuous guidance of the schema builder, through three different activities: choosin~ the most appropriate schema from a library of basic text and summary schemas or from a library of working text and summary schemas which contain the schemas utilised in previous surm~arizing sessions; tuning a selected schema by assigning (or reassigning) same parameters contained in it; defining a fully new (basic) schema. It is understood that working schemas are not requested to be always defined at the same level of detail and completeness; they are allowed to embed more or less information according to the adequacy and richness of the specifications supplied by the user. For both text and summary schemas there exist default values to be utilized when the user is unable or unwilling to supply its own