Summary Continued

• Algorithm for entailment: Does the set of FDs S entail the dependency A -> B?

  • Compute the closure of A. If it includes the attribute B, return Yes. Otherwise, return No.

• Algorithm for entailment of a set of FDs: does S entail S1?

  • Apply the previous algorithm for each FD in S1. Return Yes only if it’s Yes for all.

• Algorithm for equivalence: apply entailment in both directions.

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