ISRO | ISRO CS 2017 – May | Question 11

Given the following statements:
S1 : Every context-sensitive language L is recursive
S2 : There exists a recursive language that is not context-sensitive
Which statements are true?
(A) Only S1 is correct
(B) Only S2 is correct
(C) Both S1 and S2 are not correct
(D) Both S1 and S2 are correct

Answer: (D)
Explanation: According to Chomsky Hierarchy:
Refer: Theory of Computation | Chomsky Hierarchy
CSL languages are the subset of recursive languages, so, (S1) is correct.
Also, Recursive languages are the superset of CSL and it is not necessary that every Recursive language is CSL. So, (S2) is also correct.
Option (D) is correct.
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