Let R1 and R2 be regular sets defined over the alphabet, then

2015

Let R1 and R2 be regular sets defined over the alphabet, then

Answer: C. Σ * - R1 is regular — Regular languages are closed under complementation. Therefore, if R1 is regular, Σ* - R1 (the complement of R1) must also be regular. While union,…

  1. A.

    R1 ∩ R2 is not regular

  2. B.

    R1 ∪ R2is not regular

  3. C.

    Σ * - R1 is regular

  4. D.

    R1 * is not regular

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Correct answer: C

Regular languages are closed under complementation. Therefore, if R1 is regular, Σ* - R1 (the complement of R1) must also be regular. While union, intersection, and Kleene star operations also preserve regularity, the correct option identifies closure under complementation.

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