CODEWITHSUNDEEP
pushdown-automaton
user1191118
user1191118

Reputation: 1

Understanding details in Pushdown Automaton (PDA)

I've recently been set a task to create a Pushdown Automaton that is based on a Finite Automaton that I created beforehand. (I didn't actually do it successfully, which is why I was given a working copy by my tutor)

I'm having trouble understand a part which is included in both diagrams.

""The first is what exactly does an arrow mean when it is joint to a state but just points right back to it, am I right in thinking that this is checking that the language entered beforehand (in my case 0-9) is correct (this arrow is pointing back at a terminal state)""

I've tried doing my research but unfortunately I have come up with nothing that can really explain it to me in basic terms, I even tried "Finite Automaton for dummies" And still nothing! I've also checked questions that may have my answer and nothing there.

Upvotes: 0

Views: 247

Answers (1)

Mormegil
Mormegil

Reputation: 8071

If you mean a loop like the two arrows marked with “1” on the following diagram:

Finite state machine example

then those are just normal state transitions, the only special aspect is that the next state is the same as the previous state. I.e., if we are at the S_2 state above, then while the input contains “1”, we consume those ones and stay in S_2. Only after a “0” comes from the input we move to S_1.

In case of your specific machine, you probably should stay in the terminal state while the input contains any digit (“0–9”).

Upvotes: 1

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