For the following relation schema and sets of FD\'s R(a,b,c,d) with Fd\'s ab->c

Question

For the following relation schema and sets of FD's


R(a,b,c,d) with Fd's ab->c , bc->d , cd->a , and ad->b

A) indicate all the BCNF violationd. Do not forget to consider Fd's that are not in the given set, but follow from them. However it is necessary to give violations that have more than one attribute on the right side.
B) Decompse the relations, as necessary , into collections of relations that are in BCNF
For the following relation schema and sets of FD's


R(a,b,c,d) with Fd's ab->c , bc->d , cd->a , and ad->b

A) indicate all the BCNF violationd. Do not forget to consider Fd's that are not in the given set, but follow from them. However it is necessary to give violations that have more than one attribute on the right side.
B) Decompse the relations, as necessary , into collections of relations that are in BCNF
For the following relation schema and sets of FD's


R(a,b,c,d) with Fd's ab->c , bc->d , cd->a , and ad->b

A) indicate all the BCNF violationd. Do not forget to consider Fd's that are not in the given set, but follow from them. However it is necessary to give violations that have more than one attribute on the right side.
B) Decompse the relations, as necessary , into collections of relations that are in BCNF

Explanation / Answer

A)

Consider,

R(a,b,c,d) with Fd's ab->c , bc->d , cd->a , and ad->b

Check whether R is in BCNF.

First determine the key(s). Notice that a, b, c and d appear on the right side of any FD. if {a,b,c,d} by itself could be the key.

Relation R is in BCNF iff whenever there is a non trivial FD A1 A

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