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GATE 2021 CS (CS2) – Question 50

Databases · Integrity Constraints and Normal Forms · 2 marks · Multiple select

On U(P,Q,R,S,T), dependencies P→QR and RS→T hold. Which can be inferred?

  1. PS→T
  2. R→T
  3. P→R
  4. PS→Q

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Show answer and explanation

Correct answer: (A) PS→T; (C) P→R; (D) PS→Q

Explanation

Decomposition gives P→R and P→Q, so C holds and augmenting the latter gives D. Starting from PS, P yields R, and RS then yields T, proving A. R alone does not supply S and need not determine T. Thus A,C,D.

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