# Answer to Question #55804 in Other Programming & Computer Science for Jiahao Qi

Question #55804

Given the following table, which of the following a

re NOT functional dependencies:

a) A ->B

b) B -> A

c) (B, C) -> D

d) B -> D

e) (B, C) -> E

A B C D E (The letters A, B, C, D, and E) are columns.

X Y U L G

X Y M K H

X T U J H

W Z M J I

W Z N J I

re NOT functional dependencies:

a) A ->B

b) B -> A

c) (B, C) -> D

d) B -> D

e) (B, C) -> E

A B C D E (The letters A, B, C, D, and E) are columns.

X Y U L G

X Y M K H

X T U J H

W Z M J I

W Z N J I

Expert's answer

Solution

We can assume, that some expression is functional dependencies if for same value of left side we have same value at the right.

So, a) not functional dependencies since for A=X corresponding 2 rather value for B (Y and T).

d) not functional dependencies since for B=Y corresponding 2 rather value for D (L and K).

for all other dependencies for same value of left side corresponding same value in right side

Answer: A, D

We can assume, that some expression is functional dependencies if for same value of left side we have same value at the right.

So, a) not functional dependencies since for A=X corresponding 2 rather value for B (Y and T).

d) not functional dependencies since for B=Y corresponding 2 rather value for D (L and K).

for all other dependencies for same value of left side corresponding same value in right side

Answer: A, D

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