1. The Golden Chain εNFA  NFA  DFA  REGEX

2. Regular Expressions

4. Computations in a semi-ring Given a weighted graph, find the shortest path connecting any two vertices Given a graph, find its transitive closure Given a finite automaton, find the REGEX describing its language

5. DFA and REGEX are equivalent!

6. From DFA ro Regex: Example Will need:

8. alternative technique: State Elimination

10. Algebraic laws

11. Algebraic laws for REGEX

12. Properties of Regular Languages

13. The intuition behind the pumping lemma

15. example

16. confuting the regularity of a language

17. The pumping lemma Cannot prove that a language is regular It MIGHT be able to confute that a language is regular It does not state that in any regular language every sufficiently long string z contains a repeated term, i.e., z =xyyw