Suppose R is a relation with attributes A1 A2 An As a funct

Suppose R is a relation with attributes A_1, A_2, ...., A_n As a function of n, tell how many superkeys R has, if: The only keys are (A1, A2} and {A3, A4}. Suppose R is a relation with attributes A_1, A_2, ...., A_n As a function of n, tell how many superkeys R has, if: The only keys are (A1, A2} and {A1, A3} Prove that (X^+}^+ = (X)^+ A relation R whose schema is the set of {A, B, C, D} attributes with FDTs A rightarrow B and A rightarrow C. Either is a BCNF violation, because the only key for R is {A, D}. Suppose we start by decomposing R according to A rightarrow B. Do we ultimately get the same result as if we first expand BCNF violation to A rightarrow BC? Why or Why not? Let FD\'s be A rightarrow B and B rightarrow C. Then compare decomposing using A rightarrow B first against decomposing by A rightarrow BC first.

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