1. CS311 Automata and Complexity Theory

2. Admistrative Stuff Instructor: Shahab Baqai (baqai@lums.edu.pk) Room # 428, Ext 4428 Lectures:Mon & Wed 1530 – 1710 hrs. A-9 Tutorials:As & When needed Office Hrs:Mon & Wed 1720 – 1820 hrs TAs:3~4 (TBA) – Check course web for office hours etc Prerequisite: CS211 - Discrete Mathematics Website:http://suraj.lums.edu.pk/~cs311a04

3. Admistrative Stuff (cont.) Questions: We prefer that you post your question to the class discussion form. The TA will try to respond to all questions on the form within 24 hours (48 hours Max). This way everyone gets the benefit of reading the replies, and it helps to reduce the number of repeat questions. For questions that are not suitable to be posted to the newsgroup (e.g. questions about your grade), you can email your TA directly although there is no guarantee of when you will receive a reply.

4. Course Organization Text Book:SJ. E. Hopcroft, R. Motwani, and J. D. Ullman Introduction to Automata Theory, Languages, and Computation, Second Edition, Addison-Wesley, New York, 2001. Sections:There are two parallel sections. The material covered in each will be the same. The 6~8 assignments, midterm and Final will be common. Each section may have different quizzes. Weights:Homework06~08% Quizzes17~19% Midterm35% Final Exam40%

5. What we will do Automata = abstract computing devices Turing studied Turing Machines (= computers) before there were any real computers We will also look at simpler devices than Turing machines (Finite State Automata, Pushdown Automata,... ), and specification means, such as grammars and regular expressions. NP-hardness = what cannot be efficiently computed

6. Courtesy Costas Busch - RPI6 Computation CPU memory

7. Courtesy Costas Busch - RPI7 CPU input memory output memory Program memory temporary memory

8. Courtesy Costas Busch - RPI8 CPU input memory output memory Program memory temporary memory compute Example:

9. Courtesy Costas Busch - RPI9 CPU input memory output memory Program memory temporary memory compute

10. Courtesy Costas Busch - RPI10 CPU input memory output memory Program memory temporary memory compute

11. Courtesy Costas Busch - RPI11 CPU input memory output memory Program memory temporary memory compute

12. Courtesy Costas Busch - RPI12 Automaton CPU input memory output memory Program memory temporary memory Automaton

13. Courtesy Costas Busch - RPI13 Different Kinds of Automata Automata are distinguished by the temporary memory Finite Automata: no temporary memory Pushdown Automata: stack Turing Machines: random access memory

14. Courtesy Costas Busch - RPI14 input memory output memory temporary memory Finite Automaton Finite Automaton Example: Vending Machines (small computing power)

15. Courtesy Costas Busch - RPI15 input memory output memory Stack Pushdown Automaton Pushdown Automaton Example: Compilers for Programming Languages (medium computing power) Push, Pop

16. Courtesy Costas Busch - RPI16 input memory output memory Random Access Memory Turing Machine Turing Machine Examples: Any Algorithm (highest computing power)

17. Courtesy Costas Busch - RPI17 Finite Automata Pushdown Automata Turing Machine Power of Automata Less powerMore power Solve more computational problems