UGC-NET | UGC NET CS 2017 Jan – III | Question 19
Which of the following are not regular?
(A) Strings of even number of a’s.
(B) Strings of a’s, whose length is a prime number.
(C) Set of all palindromes made up of a’s and b’s.
(D) Strings of a’s whose length is a perfect square.
(A) (A) and (B) only
(B) (A), (B) and (C) only
(C) (B), (C) and (D) only
(D) (B) and (D) only
Answer: (C)
Explanation:
- Strings of even number of a’s is Regular because we can draw Finite acceptor(FA) for this.
- Strings of a’s, whose length is a prime number – There are infinite No. which are prime and we can’t design FA for infinite language.This is not Regular
- Set of all palindromes made up of a’s and b’s.This is not Regular because we can’t design FA for infinite language.
- Strings of a’s whose length is a perfect square.This is not Regular because we can’t design FA for infinite language.
So, option (C) is correct.
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Last Updated :
05 Apr, 2018
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