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Question

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Answer 1

后选关键字：BD
因为：BD+=(ABCD)
显然，最小依赖集为：(A->C,C->A,B->A,D->A}
所以：3NF:{AC,AC,BA,DA}={AC,BA,DA}。
可以验证，以上已经是BCNF
故：BCNF:{AC,BA,DA}。