Incorporating User Preferences in Multimedia Queries

In a multimedia database system, queries may be fuzzy: thus, the answer to a query such as (Color= 'red') may not be 0 (false) or 1 (true), but instead of a number between 0 and 1. A conjunction, such as (Color='red') (Sound='loud'), is evaluated by first evaluating the individual conjects and then combining the answers by some scoring function. Typical scoring functions include the min (the standard scoring function for the conjunction in fuzzy logic) and the average. We address the question of how to permit the user to weight the importance of atomic subformulas. In particular, we give a semantics for permitting non-uniform weights, by giving an explicit formula (that is based on the underlying scoring function). This semantics permits an efficient implementation with a low database access cost in a multimedia database system in important cases of interest.