michael sipser

Question

draw dfa

{w|w is any string not in a*b*}

????

Answer 1

all strings start with b and end with a or min string ba

or regular expression b(a+b)+

Comments

aba and many more are not accepted

Answer 2

first diagram is {w|w is any string  in a*b*}

and 2nd one is there compliment

Answer 3

Regular expression = a*bb*a(a+b)*