Which of the following statements is/are TRUE?

GATE · 2022 · CS · Computer Science & IT

1. A.

   Every subset of a recursively enumerable language is recursive.

2. B.

   If a language L and its complement L’ are both recursively enumerable, then L must be recursive.

3. C.

   Complement of a context-free language must be recursive.

4. D.

   If L1 and L2 are regular, then L1 ∩ L2 must be deterministic context-free.

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