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Mathematics, 02.12.2019 19:10 bajnathhannavanna

Let r be a relation, x a set of attributes of r, and a an attribute of r. (also, denoted by x the result of adding a to x.) define the support of x, written #x, as the number of distinct tuples in r|x (r restricted to, or projected onto, the attributes of x). prove that if x-> a, then #x=#xa. (8 points)

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Let r be a relation, x a set of attributes of r, and a an attribute of r. (also, denoted by x the re...
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