Question

Which one of the following is TRUE?

(a) The language L={a^n b^n |n>0 } is regular

(b) The language L={a^n  |n is prime } is regular

(c) The language L={w|w has 3k+1 b’s for some k } is regular

(d) None of the mentioned

This question was addressed to me in an interview.

My question is taken from Minimization of DFA topic in portion Finite Automata and Regular Expression of Compiler

Answer 1

Correct choice is (c) The language L={w|w has 3k+1 b’s for some k } is regular

The explanation is: Only  for this option we  can build a FA.