Regular Languages: Nondeterministic Finite Automaton (NFA)

How are nondeterministic finite automata (NFAs) different from DFAs? This video provides an introduction to NFAs, also one of the simple computational models and another kind of finite state machine.

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Additional resources:

- My previous video on finite state machines and DFAs. Understanding what finite state machines are exactly will be very helpful in learning about NFAs!

- I made a video on languages if you don't know what languages are.

Michael Sipser. 2006. Introduction to the Theory of Computation (2nd. ed.). International Thomson Publishing.
- The main source of my Theory of Computation knowledge (a textbook). Read Chapter 1.2: Nondeterminism to learn more about NFAs.
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And as always, this video project could not have been done without the support and guidance of Audrey St. John at Mount Holyoke College, a truly incredible professor-mentor-human.

[VahiMangai]

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[talkjoin]

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[farhanrafi]

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[houseofeufori]

Your way of explaining both DFAs and NFAs is very clear and concise, thank you so much! :)

[Ai-ghxq]

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[glitchlover]

thank you! Take my heart ❤ . Please make regular expression and it how to represent it as an nfa in next video. And again thank you so much for the effort !

[BaruchRGarcia-rmkt]

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[expansivegymnast]

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[tibetannoodles]

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[osmanyakar]

03:00 yes it accepts single "1" but; It will also accept any input sequence that contains "1". Because of the unweighted path between starting node q0 and q4, anytime when you take "1" there will be a path to q5 which is a final state. So the condition of "1 in the third final position" becomes kind of inefective.

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[khasanshadiyarov]

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[MayCodeGuide]

The video provides an in-depth explanation of Nondeterministic Finite Automata (NFAs) in contrast to Deterministic Finite Automata (DFAs). Here's a summary of the main points discussed:

Definition and Differences: NFAs, unlike DFAs, can transition into zero or more states for each symbol in the input. This characteristic makes them nondeterministic, as their next state is not always predetermined.

Examples and Acceptance Criteria: The video illustrates this concept through examples, including an NFA that accepts strings containing a '1' in the third position from the end. It highlights a key feature of NFAs: a string is accepted as long as there exists at least one path to an accept state, regardless of other possible paths that might lead to rejection.

Transition on Empty String: NFAs can also transition on the empty string, meaning they can change states without consuming any input symbols. This adds flexibility in constructing NFAs for certain languages.

Formal Definition: NFAs are defined as five-tuples, similar to DFAs, but with a transition function that can output a set of possible states instead of just one. This allows for multiple potential pathways through the automaton for a given input string.

Equivalence with DFAs: Despite the structural differences, the video concludes that NFAs are not more powerful than DFAs. Any language recognized by an NFA can also be recognized by a DFA, meaning both can define the same set of regular languages. NFAs offer a more simplified construction for certain languages without increasing the computational power beyond that of DFAs.

This explanation underscores the theoretical underpinnings of finite automata in computer science, particularly in the areas of language recognition and automata theory.

[mustapharaimilawal]

Awesome video, please do more. Thanks.

[brychjakub]

you have saved me hours with scripts I do not understand. A question: why would DFA be used if there are NFAs? wouldn't that be always easier?

[hafsaesam]

such a good work!! Thank you very much

[amrob]

Very calm and cute voice hope you are doing good in life

[ericbaptista]

Thank Could you make one for converting NFA to DFA??