Archives for July 2013

Two curses affecting Mixed-integer programming computation

In today’s last post dedicated to the #MIP2013 workshop, I examine two sources of complexity affecting research in mixed-integer (linear and nonlinear) programming. Curse of Dimensionality Although the term was coined by Richard E. Bellman in context of dynamic programming, this applies to most aspects of integer programming. Even a LP-based polytope has an exponential […]

Closing the (MIP) Gap – Part II

Day #2 of the MIP 2013 Workshop reminded me that despite the numerous research efforts invested in mixed-integer programming in the last 60 years or so, much remains to be done. A lot of MIP models are still very difficult to solve. In MIP extensions such as nonlinear, multi-objective or multi-level programming, most large-sized problems […]

The Dark Side is strong within this year’s community

This post is written in the context of the 2013 Mixed Integer Programming workshop, held in Madison WI.  It is humorous rather than serious in nature, so please do not take this post too seriously. Day #1 from MIP 2013 workshop was rich and diverse in terms of technical content. Talks from speakers such as Tobias […]

Using more cores does not necessarily lead to reduced run times on Gurobi 5.0

This post takes a look at performance variability issues when scaling up the number of processors assigned to the Gurobi MIP solver (I did the same study for CPLEX in this post a few months ago). I summarize results from a few computational experiments we’ve made. I show that while increasing the number of processor […]

Three value creation models in the OR field [dual]

I a previous primal post, I have described three generic types of value creation configurations: the shop, the chain and the network, as characterized in Stabell & Fjeldstad (1998). In this post, I apply these concepts to key players in the field of Operations Research. While names used are fictional, some players may recognize themselves in […]

Three generic types of business models [primal]

Through reading Clayton Christensen’s book Disrupting Classroom, I came across Christensen’s explanation of a framework for business models developed by Charles B. Stabell and Øystein D. Fjeldstad[1].  This framework is simple yet powerful at explaining how different organizations deliver value to their customers. This primal post is rather business-generic; in the associated dual post, I will provide […]

Experimenting with LocalSolver 3.0 [primal]

This post presents and discusses results of some experiments performed with LocalSolver 3.0, a solver based on the local search paradigm. I investigate whether LS is able to find good solutions quickly and reliably. This post is a follow-up of my first experiments with LocalSolver; I encourage you to read this if you didn’t do so already. The […]