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Question 86Asked in Bihar STET 2025 Paper II Computer Science, 3 Nov 2025, Shift 1 (9:00 AM)

The class of CFG is not closed under----

  1. AConcatenation
  2. BIntersection
  3. CUnion
  4. DRepeated Concatenation.
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Correct answer: (D) Repeated Concatenation.

Explanation

Note: the answer key gives (D), but context-free languages are closed under union, concatenation and Kleene star (repeated concatenation). They are not closed under intersection (B), for example aⁿbⁿcᵐ ∩ aᵐbⁿcⁿ = aⁿbⁿcⁿ.

From Bihar STET 2025 Paper II Computer Science PYQ, 3 Nov 2025, Shift 1 (9:00 AM)

This is question 86 of Bihar STET 2025 Paper II Computer Science PYQ, 3 Nov 2025, Shift 1 (9:00 AM). See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.