1. Automata and Formal Languages
Hongwei Xi
University of Cincinnati
Fall 2000
5 February 2019
Introduction

2. Welcome! 20-ECES-670: Automata and Formal Languages
Introduction to automaton theory, computability and computational complexity
What is the limitation of a computer?
What makes some problems inherently more difficult than others?
5 February 2019
Introduction

3. Course Overview Regular Languages: lexical analysis
Example: identifiers: [a-zA-Z][a-zA-Z0-9]*
Nonregular Languages:
Pumping Lemma(s) for regular languages
5 February 2019
Introduction

4. Course Overview Context-free Languages: programming language syntax
Example: expressions: E -> id, E -> E + E, E -> (E)
Non-context-free Languages:
Pumping Lemma(s) for context-free languages
5 February 2019
Introduction

5. Course Overview Computability Theory The Church-Turing Thesis
Turing machines
Decidability/Undecidabilty
The halting problem
Diagonalization
Reducibility
An approach to establishing undecidabilty results
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Introduction

6. Course Overview Complexity Theory Time Complexity Space complexity
The Class P
The Class NP
NP-completeness
Space complexity
The Class PSPACE
PSPACE-completeness
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Introduction

7. What is this course like?
Stressing both mathematical reasoning and implementation skill
Prove theorems
Implement algorithms
Emphasizing mathematical rigor and clarity
“If you can’t explain it, you probably don’t understand it ”
5 February 2019
Introduction

8. What is this course like?
You will have to work hard in order to keep up!
Many ideas may sound unfamiliar to you. They are often formal and take time to “sink in”.
Assignments often require both mathematical reasoning and implementation skill.
5 February 2019
Introduction

9. What this course is like?
There is an excellent textbook for this course. Get it!
Both studying and experimentation are essential to gaining understanding of the material
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Introduction

10. What is this course like?
Most of all, it’s a lot fun!
Elegant interplay between theory and practice
Rapid exposure to many fundamental ideas
Enormous potential for pursuing further studies in computer science
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Introduction

11. People
Teaching Staff
Instructor: Hongwei Xi Rhodes Hall 811 D
Teaching assistant: Monica Martin
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Introduction

12. Schedules Lectures: MWF 2-2:50AM Swift 501
Office Hours: To be announced
Or by appointment
Or stop by 811 D Rhodes
5 February 2019
Introduction

13. Programming Languages
Standard ML (preferred)
Or one of your favorites (C, C++, Java, etc.)
It is your responsibility to make sure that your code runs under Unix!
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14. Homework Approximately 10 assignments Clarity and elegance count
About one every week
Individual work only unless specified otherwise!
Clarity and elegance count
It is not enough to just “work” on test data
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Introduction

15. Exams and Grades Midterm Final Homework (25%) All exams are open-book
Monday, Oct 30
In-class (25%)
Final
Monday, Mar 13
In-class (50%)
Homework (25%)
All exams are open-book
Participation can make difference on your letter grade
5 February 2019
Introduction

16. Academic Integrity Strict adherence to the university guidelines
All work must be solely your own!
Repeat: all work must be solely your own!
If you have difficulty keeping up, ask for help!
The teaching staff are always willing to help
Ask earlier, rather than later
5 February 2019
Introduction

17. A Warning and A Plea This is my first time to offer such a course
I’m certain to make (many) mistakes
But I’ll do my best to run the course smoothly
Please be patient and ask a lot of questions
5 February 2019
Introduction

18. Course Information Everything is on the web!
Course Homepage
Notes, Slides, Handouts, Assignments, Solutions
Please visit the homepage frequently!
5 February 2019
Introduction