Question

Suppose the following functional dependencies hold on a relation U with attributes P, Q, R, S, and T:

P → QR

RS → T

Which of the following functional dependencies can be inferred from the above functional dependencies?  

1. P → R
2. PS → T
3. R → T
4. PS → Q

Answer 1

Correct Answer - Option :

Functional Dependencies are P → QR and RS → T

Option 1: Inferred

{P}+ = {PQR} 

P → R is inferred from the given functional dependencies.

Option 2 and option 4: Inferred

{PS}+ = {PSQRT}

PS → T is inferred from the given functional dependencies.

PS → Q is inferred from the given functional dependencies.

Option 3:  Cannot be Inferred

{R}+ = {R} 

R → T is not inferred from the given functional dependencies.

Therefore option 1, 2 and 4 are correct