CS262, Algorithms and Data Structures, Fall 2009
Linear Programming and Approximation Algorithms
Instructor: Marek Chrobak, Engineering II 406, x3769,
marek@cs.ucr.edu.
Office hours: Monday 2-4PM, or by appointment.
Schedule: TT 8:10-9:30AM Sproul 2212
Syllabus:
In this class we will discuss approximation algorithms for combinatorial
optimization problems. The focus of the course will be on linear programming
techniques, in particular on the role of the duality theory and various
primal-dual methods for the design and analysis of efficient approximation
algorithms. We will cover both off-line and on-line algorithms.
This is an advanced class and students are expected to possess some
prerequisite knowledge required to follow the material. Strong background
on algorithm design and analysis is required, including the
following topics: divide-and-conquer, dynamic programming,
algorithms on graphs, shortest paths, minimum spanning trees,
maximum flow, bipartite matching,
amortized analysis. Some prior exposure to linear programming and/or
to approximation algorithms is strongly recommended.
In terms of prerequisite coursework, an advanced undergraduate class on
algorithms is required, and a graduate course recommended. If you are not
sure if you have the background needed to take this class, please see
the instructor.
The class will be taught in the standard seminar format.
During the first several weeks, the instructor will present an overview
of the area and cover basic facts about linear programming, duality, and
some basic applications of the primal-dual to the design of
approximation algorithms. The remainder of the class
will consist of student presentations. A list of papers to present will be
available, and students will be allowed to propose their own topics.
Each student will give a presentation. The expected time of
a presentation will be 2 hours (about 1.5 lecture). At least a week prior
to the scheduled presentation, a brief summary of the presentation, ideally
about 5-6 pages long, needs to be submitted (LaTeX only).
The summary should contain a rough content of the presentation, and should
include some original material -- typically examples to illustrate concepts
and ideas from the presented paper. Guidelines and a template for
summary papers will be available.
These papers must be well written and fully
self-contained. They will be distributed to the whole class
and other students are encouraged to critique them.
There will be no tests. The grade will be based on the
presentation(s), the presentation summary, attendance, and activity in class.
Topics (very tentative):
- Linear programming: simplex, duality, the primal-dual algorithm
- extension of the primal-dual to approximation algorithms
- vertex cover and set cover
- dual fitting and rounding
- facility location problems: the primal-dual algorithm for facility
location, k-medians, k-centers
- Steiner trees
- Multi-way cuts
- Multi-commodity flows
- Semi-definite programming
- Primal-dual methods in online optimization
- Hardness of approximation results
- Thursday, September 24
Introduction.
A few classical results in approximation algorithms.
- Tuesday, September 29
More basic results in approximation algorithms.
- Thursday, October 1
Basic results in approximation algorithms, cont.
- Tuesday, October 6
Linear programming, duality, primal-dual.
- Thursday, October 8
Facility location, Jain-Vazirani primal-dual approximation algorithm
(last update: Wed Oct 21 15:52:23 PDT 2009)
- Tuesday, October 13
K-medians.
- Thursday, October 15
K-medians, cont.
- Tuesday, October 20
K-medians, yet again.
- Thursday, October 22
Art Rakthanmanon, paper by D.B.Shmoys, E.Tardos, K.I.Aardal, 1997.
- Tuesday, October 27
Art Rakthanmanon, cont.
David Cohen, paper by S.Guha, S.Khuller, 1998
(updated Tue Oct 27 10:47:50 PDT 2009)
- Thursday, October 29
David Cohen, cont.
- Tuesday, November 3
Changhui Lin, paper by V.Arya et all on local search
(updated Mon Nov 2 13:05:24 PST 2009)
- Thursday, November 5
- Tuesday, November 10
Changui Lin, cont.
- Thursday, November 12
Li Yan, paper by D.Fotakis on online facility location
(updated Thu Nov 12 17:37:16 PST 2009)
- Tuesday, November 17
Li Yan, cont.
- Thursday, November 19
Peng Wang, paper by K. Jain et al on greedy facility location
(updated Thu Nov 19 09:56:42 PST 2009)
- Tuesday, November 24
Peng Wang, cont.
- Thursday, November 26
No class
- Tuesday, December 1
- Thursday, December 3
Facility Location and k-Medians
- K.Jain, V.V.Vazirani, 1999,
"Primal-dual approximation algorithms for metric facility location problems"
(Not for a presentation -- I will present it myself)
- D.B.Shmoys, E.Tardos, K.I.Aardal, 1997,
"Approximation algorithms for facility location problems"
(Art Rakthanmanon)
- S.Guha, S.Khuller, 1998,
"Greedy strikes back: improved facility location algorithms"
(David Cohen)
- V.Arya, N.Garg, R.Khandekar, A.Meyerson, K.Mungala, V.Pandit,
"Local search heuristics for k-median and facility location problems"
(Changhui Lin)
- K.Jain, M.Mahdian, E.Markakis, A.Saberi, V.V.Vazirani,
"Greedy facility location algorithms analyzed using dual fitting with factor-revealing LP"
(Peng Wang)
- M.Mahdian, Y.Ye, J.Zhang,
"Approximation algorithms for metric facility location problems"
(Kind of technical ...)
- J.Byrka, K.Aardal,
"The approximation gap for the metric facility location problem is not yet closed"
(Not for a full presentation -- only additional info)
- D.Fokakis,
"A primal-dual algorithm for online non-uniform facility location"
(Li Yan)
Steiner Networks
-
D.Williamson, M.X.Goemans, M.Mihail, V.V.Vazirani,
"A primal-dual approximation algorithm for generalized Steiner network problems"
Covering and Packing
- J.Mestre,
Primal-dual approximation algorithm for partial vertex cover: making educated guesses
- N.Buchbinder, J.Naor,
Online primal-dual algorithms for covering and packing problems
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