# How do you draw a DFA from a regular expression?

I want to draw a DFA from the below language:

The set of strings in $\{a, b\}$ where every $a$ is immediately followed by $b$

I can write the regular expression for this language as so:

$$((b^*)(ab)(b^*))^*$$

How do I draw the DFA for this expression?

• In general, the procedure is to draw a non-deterministic finite automaton from the regular expression, then convert to a DFA (where the states consist of set of states of the NDFA). – Daniel Schepler Oct 21 '17 at 0:42

• $\epsilon$
• and strings such that every a is immediately followed by b $$L=\{\epsilon,b,bb,bbb,...,ab,abb,....,bab,bbababb,.... \}$$ Regular expression: $(b^*\,ab\, b^*)^*+b^*$