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Erik Jonsson School of Engineering and Computer Science

Erik Jonsson School of Engineering and Computer Science. CS 4384 – 0 01. Automata Theory. http://www.utdallas.edu/~pervin. Thursday: Context-Free Languages Chapter Three. Tuesday 3-18-14. FEARLESS Engineering. Context-free Languages. Chapter Three. Palindromes. Chomsky Normal Form.

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Erik Jonsson School of Engineering and Computer Science

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  1. Erik Jonsson School of Engineering and Computer Science CS 4384– 001 Automata Theory http://www.utdallas.edu/~pervin Thursday: Context-Free Languages Chapter Three Tuesday3-18-14 FEARLESS Engineering

  2. Context-free Languages Chapter Three

  3. Palindromes

  4. Chomsky Normal Form

  5. Other Simplifications Useful variables and productions Left-recursion

  6. Useless Example

  7. Left-recursion 3-04-14

  8. Pushdown Automata Many similar definitions

  9. STACK

  10. JFLAP PDA Example

  11. What if the input does not have a middle separator so we do not know when to start the comparison between the input and the stack? Non-determinism!

  12. 4. Cohen PDA

  13. Odd Palindrome

  14. Even Palindrome

  15. CFG » PDA

  16. S -> aSb | ab => S -> X_aY | X_aX_b ; Y -> SX_b; X_a -> a ; X_b -> b

  17. PUMPING LEMMA Context-Free 3-6-14

  18. Sipser, P. 116

  19. NOTE: CFLs are not closed under intersection (or complement)!

  20. Martin, P. 218; H&U, P. 115

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