RANDOMIZED ALGORITHMS (randomiserade algoritmer)

period IV (March-May), 2006

Course code: TMS081 (at Chalmers) and MSN420 (at GU).

The course gives 5.0 credit units (at Chalmers or at GU).

Instructor: Johan Tykesson (J.T.), email johant@math.chalmers.se

Email list: I maintain an email list for information pertaining to the course. If you want to be on this list, contact me (J.T.) and I will put you on the list. You can also sign up on the list on the first lecture.

Click here to download this year's home exam: ps-file and pdf-file.

Course content: That randomization (the use of random numbers in computer algorithms) in many situations leads to better and faster algorithms, is a fundamental but fairly recent insight. The purpose of the course is to communicate this insight, and to provide familiarity with randomized algorithms and their mathematical foundations. Topics covered are
  • Mathematical foundations, including probabilistic methods and Markov chains.

  • Randomized algorithms for, e.g., sorting, Monte Carlo integration, stochastic simulation, approximate counting, and various combinatorial and/or geometrical optimization problems.

  • Analysis of the complexity of randomized algorithms.
A part of the course consists of a project, where the students have the opportunity to apply the above to some concrete application, or to deepen their theoretical knowledge in some specific direction (or both!).


NEW!

Hand in task: Solve some of the following excercises from the book: 2.3, 2.7, 3.1, 4.4, 5.3, 6.1, 7.4, 9.3, 10.2, 11.2, 13.1, 13.2. You are allowed to cooperate, but everyone must hand in their individually written solutions, and be prepared to defend the solutions. It is not necessary to hand in all solutions at once, but all solutions must be handed in before 31st of May, 2006. You must hand in at least 6 acceptable solutions. 8 correct solutions give 1 bonus point on home exam. 10 correct soultions give 2 bonus points on home exam. 12 correct solutions give 3 bonus points on the home exam.

Lectures: There will be approximately 10 lectures. This year the lectures are scheduled on Tuesdays 13-15 in MVF26 and Fridays 10-12 in MVF33 in the new mathematics building.

The project homepage is here. Please note that it may be updated with more projects later!

Lecture 1:Two basic examples of randomized algorithms: Calculation of area using the Monte Carlo Method and the Random Quicksort algorithm for sorting. These examples are not covered by the coursebook. The quick sort example was taken from the book "Randomized Algorithms" by Rajeev Motwani and Prabhakar Raghavan. Tue 14 March 13.15-15.00 MV:H11
Lecture 2:Introduction to Markov Chains. From the book we will cover in essential pages 8-12, and do problem 2.1. Fri 17 March 10.00-11.45 MV:F33
Lecture 3:Introduction to Markov Chains. We covered simulation of Markov chains, aperiodicity, irreducibility, and did a short introduction to stationary distribution. Tue 21 March 13.15-15.00 MV:F26
Lecture 4:Introduction to Markov Chains: Stationary distributions: existence, uniqueness and convergence (Chapter 5). Reversible Markov chains (Chapter 6). Exercises 5.4 and 6.3 will also be solved. Tue 28 March 13.15-15.00 MV:F26
Lecture 5:Markov Chain Monte Carlo: Introduction and the hard core model. Fri 31 March 10.00-11.45 MV:F33
Lecture 6:Markov Chain Monte Carlo: q-coloring of graphs and Metropolis Hastings. Tue 4 April 13.15-15.00 MV:F26
Lecture 7:Optimization using randomized algorithms: Simulated annealing. Fri 7 April 10.00-11.45 MV:F33
Lecture 8:Approximate Counting. Tue 25 April 13.15-15.00 MV:F26
Lecture 9:Propp-Wilson. Fri 28 April 10.00-11.45 MV:F33
Lecture 10:Sandwiching. Tue 2 May 13.15-15.00 MV:F26
Lecture 11:Game tree evaluation. Fri 12 May 10.00-11.45 MV:F33
Lecture 12:Some problems from some old home exams. Tue 16 May 13.15-15.00 MV:F26

Some problems from the book (chapter 2) for those who has not bought it yet: PS-file and PDF-file.

Lecture notes from 2004 written by the lecturer of 2004, Fredrik Lundin. Note that my notes will differ from his, but they are both based on the book by Häggström.

Literature: Chapters 2-12 in "Finite Markov Chains and Algorithmic Applications" by Olle Häggström, one of the professors at our department. You can find it using bokfynd. The are also some available at Cremona.

Examination consists of three parts:

To pass the course, you must pass all three parts. What grade you get (3, 4 or 5 for Chalmers students, and G or VG for GU students) is determined by the score on the home exam:

The home exam will give a maximum of 20 points. The grading is then at follows. For Chalmers, you will need 8 points for a 3, 12 points for a 4 and 16 points for a 5. GU-students will need 9 points for a G and 15 points for a VG.

Here are some old home exams: 2002, 2003, 2004, 2004 with solutions.

Prerequisites: Necessary prerequisites for the course, are to have taken (and passed!)


Last modified: 20060321 by Johan Tykesson.