Class of language

Question

Answer 1

(A) L is regular
L = {w | w contains equal number of ab and ba }:

strings in language: eps, a*, b*, aba, abbbbba ababa ....
Regular Expression: $ eps+ a(a + bb^{*}a)^{*} + b(b + aa^{*}b)^{*}$

DFA:

Answer 2

L is regular..

just ensure that if you start with 'a' you should end with 'a' and if start with 'b' then end with 'b'....

dfa will be.

Comments

yes it is same as saying that , language that start and end with the same letter.

Answer 3

Ans : B. L is a DCFL but not regular