How problematic are your Big M constraints? an experiment [primal]

This post investigates whether it is still relevant to be careful about the coefficients used in so-called Big M constraints when formulating mixed-integer programming (MIP) models. I make some experiments with two-echelon supply chain design models to show that using too large values often cause the models to be harder to solve. The impact is much greater […]

The recommendation game [primal]

People who teach or supervise students have a tremendous influence on what solvers get adopted by the operations research / industrial engineering community. Once they finish their studies, many students will continue to use the tools they have learned in school, for many reasons. First, it is simply the most efficient strategy to adopt. Also, […]

Distributed MIP solving reaches Gurobi [primal]

Distributed optimization has now reached the point where it is incorporated into general-purpose mixed-integer programming (MIP) solvers such as CPLEX and Gurobi. In today’s post, I will summarize the implications of some results presented at the INFORMS 2014 annual conference by Dr. Ed Rothberg. You can see the full slide deck here. The associated dual post presents some of […]

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 […]

5 reasons why solver developers should listen to academia [primal]

We academia enjoy giving advice to others. Here are a few reasons why solver developers should sometimes listen to what academia have to say. You can get a set of opposite arguments on the associated dual post.