COMS W3261
Computer Science Theory
Lecture 8: October 1, 2012
Pushdown Automata

Outline

1. Review

2. Pushdown Automata

3. Instantaneous Descriptions

4. The Language of a PDA

5. Deterministic Pushdown Automata

6. From a CFG to an equivalent PDA

7. From a PDA to an equivalent CFG

8. Practice Problems

  1. Construct a PDA that accepts { wcwR | w is any string of a's and b's } by final state.
  2. Construct a PDA that accepts { wcwR | w is any string of a's and b's } by empty stack.
  3. Construct a PDA that accepts { wwR | w is any string of a's and b's } by final state.
  4. Construct a PDA that accepts { wwR | w is any string of a's and b's } by empty stack.
  5. Construct a PDA P such that N(P) = L(G) where G is S → (S)S | ε.

9. Reading Assignment



aho@cs.columbia.edu