Show how to derive the following equivalences by a sequence
Show how to derive the following equivalences by a sequence
Show how to derive the following equivalences by a sequence of transformations using the equivalence rules in Section 14.3.1.
a. σθ1 ∧ θ2 ∧ θ3 (E) = σθ1 (σθ2 (σθ3 (E)))
b. σθ1 ∧ θ2(E1 1θ3 E2) = σθ1 (E1 1θ3 (σθ2 (E2))), where θ2 involves only attributes from E2