Lecture 21

Today:

• 1. Quiz.

  2. NP completeness.

  3. Ideas for DYI module.

For next time:

• 1. Start Homework 11.

  2. Reading questions below.

Reading questions

Sipser, pages 283-295 and some of Chapter 5.

1) What's a gadget?

[Read the proof of Theorem 7.44 carefully, then skim the other proofs in Section 7.5.]

2) Make a list of the problems in Chapter 7 that are shown to be NP-complete. For each problem write a short description of what the problem is and the technique used to prove its NP-completeness.

3) Do exercise 7.10 on page 295, "Show that ALL_{DFA} is in P."

[Go back to page 197 and read the proof that ALL_{CFG} is undecidable.]

4) Do exercise 5.1 on page 211, "Show that EQ_{CFG} is undecidable."

5) Do problem 5.16 on page 212, (The busy beaver function).