# Does finding a reversal of a regular expression by automata need automata to be a DFA?

If I want to find the reversal of a regular expression using an automata, Do I have to transform the automata to DFA if it wasn't ?

• Colleague Vor has demonstrated that inverse (mirror image) of the language of a regular expression can be found by merely inverting the expression itself. So why would you use the automaton? Jul 26 '21 at 19:45

• Add a new initial state $$q_0$$, and add a transition (edge) $$q_0 \overset{\varepsilon}{\to}q$$ towards every state (vertex) $$q$$ that formerly was an accepting state.