Formal systems for join dependencies (Q1071524)

The existence of sound and complete formal systems for the implication problem for join dependencies is deeply investigated. One such system (Gentzen-style and having an inference rule with an unbounded number of premises) is found. Extended join dependencies are defined, and two other sound and complete formal systems are obtained: a bounded system for join dependencies using only generalized join dependencies in the derivation, and an unbounded system for extended join dependencies. Both systems are sound and complete also for tuple generating dependencies.