Qualifying answers according to user needs and preferences

摘要: This paper presents a rigorous methodology for using annotated logic programming techniques to handle user preferences and needs in answering database queries. Two alternative transformations turn program into new that returns answers queries according qualitative labels. The two have different semantics are each appropriate situations. We modified the standard definitions of programs databases. In formalism, provides lattice domain-independent values define set domain specific constraints qualified with values. After original been transformed deductive database, query-answering procedures databases used, minor modifications, obtain Because preference declaration is separated from data representation management, can be easily altered without touching database. resulting query language allows users ask at levels.