Reasoning about qualitative trends in databases

摘要

We propose a temporal constraint, called trend dependency (TD), which captures a significant family of qualitative trends in databases. An important extension in comparison with existing temporal dependencies is that TDs allow attributes with linearly ordered domains to be compared over time by any operator of {<,=,>,⪯,≥,≠ n0 –} sound and complete axiomatization for logical implication of TDs is provided. The complexity of the logical implication problem for TDs is investigated. A comparison with related work is provided at the end of the paper. We show that TDs can express most temporal dependencies that have so far been proposed in the literature.