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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. Tuesday: Context-Free Languages Chapter Three – Review All. Thursday 4-03-14. FEARLESS Engineering.

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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 Tuesday: Context-Free Languages Chapter Three – Review All Thursday4-03-14 FEARLESS Engineering

  2. A search of Albert Einstein's archived manuscripts last year turned up a draft of an early unpublished paper by the famed physicist that concluded, mistakenly, that new matter, such as stars and galaxies, would appear to fill the expanding universe. Einstein was attempting to make sense of Edwin Hubble's observation that the universe was expanding, but he made a mathematical error. When he discovered his mistake, he set aside the paper, which is now in a digital archive of his papers at the Hebrew University in Jerusalem. Waterford Institute of Technology physicist Cormac O'Raifeartaigh and colleagues found the paper while scouring the archive.

  3. Context-free Languages Chapter Three

  4. Palindromes

  5. Chomsky Normal Form

  6. Other Simplifications Useful variables and productions Left-recursion

  7. Useless Example

  8. Left-recursion 3-04-14

  9. Pushdown Automata Many similar definitions

  10. STACK

  11. Odd Palindrome

  12. Even Palindrome

  13. CFG » PDA

  14. PUMPING LEMMA Context-Free

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

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

  17. CS 341 – UT-Austin

  18. CS 341 – UT-Austin

  19. Informal Verbal PDAs

  20. Read and push a’s onto the stack; read b’s and match them against the stack until empty; read any additional b’s and push them onto the stack; read and match c’s with stack exactly.

  21. For each a read, non-deterministically push ONE or TWO a’s on the stack; then match b’s read exactly with stack.

  22. Ambiguity Dangling ELSE Problem

  23. “An ELSE belongs to the last preceding IF for which there is no ELSE already”

  24. Deterministic Pushdown Automata

  25. Martin, P. 172 Corrected

  26. End of File (EOF): UNIX Control-D (ASCII 04) Windows Control-Z (ASCII 26) Java’s Buffered Reader Null (ASCII 0) Empty Stack ($), (Zo) End of File; Empty Stack

  27. PARSING

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