Operations Research Seminar

SFU Operations Research Seminar

Welcome to the Web pages of the SFU Operations Research Seminar Series.

We are associated with:

Our aim is to meet and discuss Operations Research topics.

Regular Meeting time: Thursdays, 3:30pm to 4:30pm

Meeting place: Room 14-400, SFU Surrey, 14^th floor of the Tower.

If you are interested in giving a talk, please contact Tamon Stephen, tamon at sfu ca.

January 8

**Friday, 12:30**

M.Sc. Thesis defense (senior supervisor: Abraham Punnen)

December 3

**Thursday, 11:30**

M.Sc. Thesis defense (senior supervisor: Zhaosong Lu)

November 16

SUR 14-400

and

IRMACS 10901

Abstract:

A gene family is a set of genes, present in the genomes of several genomes,

possibly in multiple occurrences in some genomes, that all originates from a

single ancestral gene. A gene tree is a binary tree that describes evolutionary

relationships between the genes of a same family, in terms of three kinds of

events: speciations, duplications and losses.  Phylogenomics aims at inferring,

from a set of gene trees, a species tree.  Here we consider the following

NP-complete optimization problem: infer the species tree that minimizes the

number of gene duplications. I will present two results:

- a description of tractable sets of gene trees (work with J.-P. Doyon and

  N. El-Mabrouk, Universite de Montreal)

- approximation algorithms for computing a parsimonious first speciation,

  based on edge-cut problems in graphs and hypergraphs (work with

  A. Ouangraoua and K. Swenson, Universite du Quebec a Montreal)

November 2

SUR 14-400

and

IRMACS 10901

Abstract:

In this seminar, main definitions and theorems of multiple objective programming

(a linear programming consisting of several objective functions) will be

mentioned. Also, solving bi-objective programming will be discussed by

extending simplex method for solving these problems.

(We assume familiarity with simplex method.)

October 26

SUR 14-400

and

IRMACS 10900

Abstract:

The max-cut algorithm of Goemans and Williamson is 15 years old in 2009, and

its impact in the area of semidefinite programming has been remarkable. In this

talk, I will survey some of the main modelling and algorithmic developments

since 1994 in the application of semidefinite programming to discrete

optimization problems. I will also highlight promising directions for research in

this area.

October 5

Abstract:

While there was much attention given to solving inverse problems there is a gap

in the question of design, that is, the design of experiments for ill-posed

problems and the design of regularization functionals.

In this talk we will present a framework to attack this problem. We show that it

leads to a stochastic bilevel optimization problem and suggest algorithms for its

solution.

September 16

*Wednesday*

**3:30**

Abstract:

A bilevel programming problem is a sequence of two optimization problems

where the constraint region of the upper level problem is determined implicitly by

the solution set to the lower level problem. Bilevel programming problems can be

used to model many problems in operations research and are also known as the

Stackelberg games in economics. In this talk we discuss difficulties of deriving

necessary optimality conditions for bilevel programming problems, in particular

when the lower level problem is nonconvex. We provide a new necessary

optimality condition which is valid under very weak constraint qualifications.

Archives of 2005-6, 2006-7, 2007-8 and 2008-9 Seminars.

Organizer: Tamon Stephen, e-mail: tamon at sfu ca.

Modified: January 6th, 2010.