Representing regular expressions with DFA state diagrams

Question

I have these regular expressions:

a) 0(10)*

b) a(b+c+d)

c) b*(aa*b*+ε)

I created these state diagrams for them:

Solutions

Are they correct?

Please post a representation of your problem directly in this forum. People are far to savvy to click on arbitrary links. — mevets, Jan 15 '23 at 10:12
Couldn't you wait for 16:20 to post this (4:20 pm), would have been nice. Also good that you're charging your phone. Usually asking a question is a way to get an answer, the more information you provide the better the chances for getting an answer. — Buttered_Toast, Jan 15 '23 at 11:29

score 1 · Answer 1 · answered Jan 15 '23 at 12:36

If I deciphered your writing correctly, this is what you wrote:

a) 0(10)*

Correct.

But two remarks:

Clearly indicate which state is the starting state. It is common to use an incoming arrow for that, like you did in answer to (c).
The rightmost two states are not really needed as they are indistinguishable from the first two states (at the top).

You could simplify to this:

b) a(b+c+d)

Not correct. There are these issues:

a is not a valid input, so the second state should not be an accepting state.
This first sink state lacks a transition for a. Once that is corrected, it becomes a state that is indistinguishable from the second sink, and so they could be merged
And you should indicate which is the starting state

Correction:

c) b*(aa*b*+ε)

Correct!

1 Answers1