Robert J. Gaizauskas
The author presents a formal theory of answers for first order de ductive database systems. Starting with the assumptions that a database is any set of closed formulas in first order logic and that a query is any formal, open or closed, in first order logic, he takes a number of informal intuitions about what answers to queries should be like and devises a formal theory that captures these intuitions. In his formal theory answers are a particular sort of formal object - sets of substitutions with certain characteristics. He goes on to investigate what might loosely be termed the compositional properties of these formal objects.
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