GATE DA 2025 | Question 26

MSQ · 1 mark

Which of the following statements is/are correct in a Bayesian network?

  1. Option A: Variable elimination is an approximate inference algorithm
  2. Option B: Gibbs sampling is an exact inference algorithm
  3. Option C: Variable elimination is used to determine conditional probabilities (correct)
  4. Option D: Rejection sampling is an approximate inference algorithm (correct)

Answer

(C), (D)

Explanation

  • Variable elimination is an exact method. It multiplies the relevant conditional probability tables and sums out the hidden variables one at a time, so A is false.
  • What it returns is a conditional probability such as \(P(Q \mid e)\) for a query \(Q\) given evidence \(e\), so C is true.
  • Gibbs sampling and rejection sampling both estimate probabilities from random samples. Their answers are approximate and improve as more samples are drawn, so B is false and D is true.

Answer: C, D