# Grand Test TOC Q15

+1 vote

S1: If X is any CFL and Y is any regular language, X ∩ Y must be regular.

S2 : If X and Y are each CFL's and neither X nor Y is regular, then$X \cup Y$ must be a CFL and X ∪ Y must not be regular.

Which of the above statement is/are CORRECT ?

A. Only S1

B. Only S2

C. Both S1 and S2

D. Neither S1 nor S2

asked Dec 10, 2019 in TOC
reshown Dec 11, 2019

## 2 Answers

+1 vote

Best answer

Answer : D

S1 : Take  $X = a^nb^n; Y = \Sigma^* ; \,\,\,X \cap Y = X(Non-regular\,\,CFL)$

S2 : Take $X = a^nb^n; Y = \bar{X};\,\,\,X \cup Y = \Sigma^*$

answered Dec 11, 2019 by (7,500 points)
selected Dec 14, 2019
0 votes
S1-F

S2-F

both are incorrect

so d is correct one.
answered Dec 11, 2019 by (34,630 points)
Answer: