COMS W3261
Computer Science Theory
Lecture 9: October 3, 2012
CFGs and PDAs

Outline

1. From a CFG to an equivalent PDA

2. From a PDA to an equivalent CFG

3. Eliminating Useless Symbols from a CFG

4. Eliminating ε-productions from a CFG

5. Eliminating Unit Productions from a CFG

6. Putting a CFG into Chomsky Normal Form

7. Practice Problems

  1. Eliminate useless symbols from the following grammar:
  2. S → AB | CA
    A → a
    B → BC | AB
    C → aB | b
    
  3. Put the following grammar into Chomsky Normal Form:
  4. S → ASB | ε
    A → aAS | a
    B → BbS | A | bb
    C → aB | b
    

8. Reading Assignment


aho@cs.columbia.edu