GATE | GATE CS 1999 | Question 29
If L1 is a context free language and L2 as a regular language, which of the following is/are False?
a. L1-L2 is not context free
b. L1 ∩ L2 is context free
c. ~L1 is context free
d. ~L2 is regular
(A) Only b
(B) Only c
(C) Both a and c
(D) Both b and c
Explanation: Given L1 is a context free language and L2 as a regular language then L1-L2 is context free language and ~L1(complement of context free) is not context free because context free is not closed under complement.
Complement of regular language i.e. ~L2 is also regular ( so d is correct ) since statements a and c are false.
Option (C) is correct.
Quiz of this Question
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