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Let $R_1$ and $R_2$ be regular sets defined over the alphabet, then

  1. $ R_1 \cap R_2$ is not regular
  2. $R_1 \cup R_2$ is not regular
  3. $\Sigma^* - R_1$ is regular
  4. $R_1^*$ is not regular
in Theory of Computation by Veteran (105k points)
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2 Answers

+10 votes
Best answer
option C is correct

Regular sets are closed under union, intersection, complement, and kleen closure

But regular sets are not closed under infinite union
by Active (3.5k points)
selected by
+1 vote

"Regular languages are closed under Intersection, Union ,Kleens Closure ,Compliment"

According to this point option C is perfect

by Boss (42.4k points)
Sir  can you give example where
$\sum*   - R1$ is not regular
∑∗−R1 is regular, this statement is true, not false.
Oh soory Sir, i didn't read the options carefully
ok sir
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