Bipolar queries: An aggregation operator focused perspective

The concept of a bipolar query, meant as a database query that involves both negative and positive conditions, is discussed from the point of view of flexible database querying and modeling of more sophisticated intentions and preferences of the user. The aggregation of matching degrees against the negative and positive conditions to derive an overall matching degree is considered taking into account as the point of departure the Lacroix and Lavency's (1987) [1] approach and the semantics of these conditions. Three variants of formalization of the “and possibly” operator which governs the adopted aggregation mode of the negative and positive parts of a bipolar query are proposed. These variants take the form of logical formulas whose logical connectives may be modeled using fuzzy logic in many different ways. New recommendations as to the choice of such variants and sets of logical connectives, which preserve the assumed semantics of the “and possibly” operator, expressed as a number of postulated plausible, or desired, properties of aggregation, are formulated.