Question

Which of the following statements is not true?

(a) Every language defined by any of the automata is also defined by a regular expression

(b) Every language defined by a regular expression can be represented using a DFA

(c) Every language defined by a regular expression can be represented using NFA with e moves

(d) Regular expression is just another representation for any automata definition

This question was addressed to me in exam.

The query is from DFA to Regular Expressions topic in chapter Regular Expressions and Languages of Automata Theory

Answer 1

Correct choice is (b) Every language defined by a regular expression can be represented using a DFA

To elaborate: Using NFA with e moves, we can represent all the regular expressions as an automata. As regular expressions include e, we need to use  e moves.