Relationlog: A Typed Extension to Datalog with Sets and Tuples (Extended Abstract)

This paper presents a novel logic-based language for nested relations. It stands in the same relationship to the nested relation model as Datalog stands to the relational model. The main novelties of the language are the mechanisms for representing both partial and complete information on sets and tuples, and the introduction of a new ordering on interpretations that captures the intended semantics for nested sets, tuples and relations. Under appropriate stratification restrictions, it is shown that the unique minimal and supported model, if it exists, can be computed bottom-up, and therefore used as the intended semantics of the program.