数据库系统基础教程第四章答案(13)

.

4.2.5

From Augmentation rule of Functional Dependency,

given

B -> M (B=Baby, M=Mother)

then

BND -> M (N=Nurse, D=Doctor)

Hence we can just put an arrow entering mother.

a) Put an arrow entering entity set Mothers for the simplest solution (As in fig. 4.4, where a multi-way relationship was allowed, even though Movies alone could identify the Studio). However, we can display more accurate information with below figure.

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