Remember that Thursday’s class will be Barbara Liskov’s talk in Chemistry Auditorium. This is at the same time (2:00pm) as our class normally meets.

Everyone should find Prof. Liskov’s talk interesting and exciting. You can read more about the talk and her background here: *www.liskovatuva.com*.

Class 18 slides: [PDF] [PPTX]

Sorry to be so rushed for the last part of class today. We’ll spend more time in next Tuesday’s class on undecidable and decidable properties of programming languages.

Problem Set 4 Comments: [PDF]

Next week there will be two Turing award winners visiting UVa and giving public talks.

**Monday, 29 March, MEC 205 (CHANGE IN VENUE), 3:30pm**

Edmund Clarke, Carnegie Mellon University

*Model Checking: My 27 year Quest to Overcome the State Explosion Problem*

**Thursday, 1 April, Chemistry Auditorium, 2:00pm**

Barbara Liskov, MIT

*Security of Internet Storage*

Note that Thursday’s talk is during our scheduled class time. Students should attend Prof. Liskov’s talk (and expect to have questions on the exam based on her talk).

Class 17 slides: [PPTX] [PDF]

Exam 1 Final Comments: [PDF]

This paper by Ron Rivest provides an interesting application of squarefree sequences, and describes (in Section 7) some interesting ways to create arbitrarily long squarefree sequences: *Abelian square-free dithering for iterated hash functions*.

Class 16 slides: [PPTX] [PDF]

This chapter: Chapter 12: Computability [PDF] from my introductory computer science textbook covers some of the things from today’s class and Chapter 4 and 5 of Sipser’s book. It is not required reading for cs3102, but hopefully some of you will find it helpful and interesting. (If you do have any comments on it, please send them to me. They are much appreciated.)

Problem Set 5 is here: [PDF] [LaTeX template]

Note that the deadline for PS5 has been postponed one week from the original syllabus schedule. It is now due on Tuesday, April 6 (2:00pm).

From now on, my Thursday morning office hours will be from 8:45am-10am (not as previously scheduled from 8:30am-9:30am).

Your reading assignment for this week (and for PS4) is Sipser’s Chapter 3, *The Church-Turing Thesis*. This chapter contains what I think is perhaps the most bogus sentence in the entire book. If you can find it, there will be at least a token reward for the first correct answer. Post your guesses and explanations (why you think its bogus) as comments here.

Class 14 slides: [PDF] [PPTX]

Problem Set 4 is here: [PDF] [LaTeX template]

PS4 is due Tuesday, 23 March (one week from today).

There will be no regularly scheduled office hours this week, but I am available for appointments, just send email to arrange a meeting. Enjoy your Spring Break!

If you do want to get ahead on the course over spring break, the next reading assignment is Chapter 3 in the Sipser book. This is what Problem Set 4 will cover, and it is due on Tuesday, March 23.

I won’t be holding office hours today. Regular office hours will resume after spring break.

Exam 1: [PDF]

Exam 1 Preliminary Comments: [PDF]

Read the revision opportunity information at the top of the Exam 1 preliminary comments handout carefully. Revised answers are due at the beginning of the next class (Tuesday, March 16, 2:01pm).

I won’t be able to hold office hours this Thursday morning. I will have my usual office hours after class Thursday.