GATE | GATE CS Mock 2018 | Question 62

A language L is called Turing-decidable (or just decidable), if there exists a Turing Machine M such that on input x, M accepts if x ∈ L, and M rejects otherwise. L is called undecidable if it is not decidable.
Which of following option is false?

(A) The class of decidable languages is closed under complement.
(B) The class of decidable languages is closed under union
(C) The class of decidable languages is closed under intersection
(D) None of these


Answer: (D)

Explanation: The class of decidable languages is closed under union, intersection, and complementation.
Option (D) is correct.

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