Oktay Günlük


http://www.research.ibm.com/people/o/oktay/

Short Bio:
I did my undergraduate and M.S. in Istanbul at Bogazici University, Dept. of IE.
I received my Ph.D. from
Columbia University, Dept. of IEOR where I worked with Dan Bienstock.
After Columbia, I spent a year at
CORE (Belgium) as a postdoctoral fellow and two years at Cornell University, School of ORIE as a visiting scientist.
In 1997 I joined the OR department at AT&T Labs and in 2000 I moved to the Math Sciences Department at IBM.


General Research Interests:
Mixed-integer programming, combinatorial optimization, multicommodity flows. Modeling, optimization and computation, especially applied to logistics, routing, workforce scheduling and network design.

Professional Life:
My professional life at the Math Department at IBM is a mix of academic research and consulting projects. In terms of project work, we are typically approached after a big customer (including governments) has shown interest in an optimization application and "real" consultants have seen an opportunity for heavy duty optimization techniques. Before we go visit the customer we usually have email/phone conversations to get a good idea about the optimization problem and based on that we often do some reading to learn the issues related with the application. For example a couple of years ago we did a routing/scheduling project for the Port of Singapore and before we visit the customer we found a few very useful papers that helped us understand the general problem and existing solution approaches. The particular problem that the customer needs to solve is always different from what one finds in academic papers. Depending on the agreement with the customer, we are sometimes able to publish papers describing the problem and our solution approach. However, this is not always the case and after the Singapore project, we could not even talk about it in conferences. In a different project, we helped a high-end limousine company "continually" optimize its operations. What we did was a nice application of column generation to solve a set cover problem where columns are daily routes of cars and items to be covered are the customers that need transport. In this project, we were able to write and publish a paper without using the name of the customer.

Even though there are some opportunities to publish papers based on projects, these are usually applied papers with limited new theory. The second half of my professional life at IBM involves doing academic research on theoretical problems. I have done a lot of work on generating cutting panes for mixed-integer programs. For example, one recent topic of interest is generation of cutting planes using lattice-free polyhedra. Even though it sounds complicated, the underlying idea is very basic and a lot of known cutting-planes actually of this type. In a recent paper with Sanjeeb Dash (a colleague at IBM) and Santanu Dey (Prof. at Georgia Tech) we showed a very interesting relationship between cuts from 2-dimensional lattice-free sets and cuts from two-term asymmetric disjunctions. I got interested in this topic more than a year ago and wrote a paper on a related topic with Ricardo Fukasawa who was a post-doc at IBM last year and is a Prof. at Waterloo now. Later I invited Santanu Dey to visit IBM for a few days to discuss related problems and Sanjeeb Dash also got interested and we started working on it together. In terms of academic research, we have full academic freedom at IBM and can work on problems that we like. If there is project work, however, it takes priority over research and we need to park or slow down research activity. This has happened to me several times.

In addition to project work and research, we also do some service to the academic/professional community. In the past I have helped organize workshops, conferences, did refereeing and editorial work for academic journals and participated in NSF panels. Currently, I am the vice chair for Integer Programming in the Informs Optimization Society and I am putting together the Integer Programming session in the next two Informs conferences. I also serve in the editorial boards of a couple of journals.