Question

Why bcnf is stronger than 3nf?

Answer 1

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ANSWER

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bcnf is stronger than 3nf because a relation R is in 3NF if and only if every dependency A->B satisfied by R meets at least ONE of the following criteria:

1. A->B is trivial (i.e. B is a subset of A)

2. A is a superkey.

3. B is a subset of a candidate key BCNF doesn't permit the third of these options. Therefore BCNF is said to be stronger than 3NF because 3NF permits some dependencies which BCNF does not.