1. Non Deterministic Automata

2. Nondeterministic Finite Accepter (NFA) Alphabet =

3. Nondeterministic Finite Accepter (NFA) Alphabet = Two choices

4. Nondeterministic Finite Accepter (NFA) Alphabet = Two choices No transition No transition

5. First Choice

6. First Choice

7. First Choice

8. First Choice “accept”

9. Second Choice

10. Second Choice

11. Second Choice No transition: the automaton hangs

12. Second Choice “reject”

13. Observation An NFA accepts a string if there is a computation of the NFA that accepts the string

14. Example is accepted by the NFA:

15. Lambda Transitions

18. (read head doesn’t move)

20. “accept” String is accepted

21. Language accepted:

22. Another NFA Example

26. “accept”

27. Another String

34. “accept”

35. Language accepted

36. Another NFA Example

37. Language accepted

38. Formal Definition of NFAs Set of states, i.e. Input aplhabet, i.e. Transition function Initial state Final states

39. Transition Function

43. Extended Transition Function

46. Formally It holds if and only if there is a walk from to with label

47. The Language of an NFA