Memory Minimization

As I grow older, I’m starting to forget things (such as all the math I ever learned) … but that’s not the reason for the title of this post. A somewhat interesting question popped up on Mathematics StackExchange. It combines a basic sequencing problem (ordering the processing of computational tasks) with a single resource constraint …

More

Premature Obituaries

[T]he report of my death was an exaggeration. (Mark Twain, 1897) In a recent blog post, “Data Science Is Not Dead“, Jean-Francois Puget discussed and dissented with a post by Jeroen ter Heerdt titled “Data Science is dead.” Barring the possibility that Schroedinger shoved data science into a box and sealed it, both assertions cannot …

More

Pro Bono Analytics Is Growing Social

Pro Bono Analytics is a program by INFORMS (the Institute for Operations Research and the Management Sciences, for the acronym-averse), “the largest society in the world for professionals in the field of operations research (O.R.), management science, and analytics”. PBA “connects our members and other analytics professionals with nonprofit organizations working in underserved and developing communities”. …

More

Better Estimate, Worse Result

I thought I might use a few graphs to help explain an answer I posted on Quora recently. First, I’ll repeat the question here: In parametric optimization with unknown parameters, does a better estimator of the parameter always lead to better solutions to the actual problem? Here we’re trying to minimize f(x,θ) with respect to …

More

Another OR Educational Resource

Two years ago (two years and one day if you’re being picky), I posted a pointer to a Spanish language web site hosted by Francisco Yuraszeck (professor at the Universidad Técnica Federico Santa María in Viña del Mar, Chile). The site, Gestión de Operaciones, is listed in the resources box on the right. Recently, Francisco …

More

ORiginals – Videos About Research

ORiginals is a YouTube channel co-hosted by Dr. Banafsheh Behzad (@banafsheh_b) of CSU Long Beach and my colleague Dr. David Morrison (@drmorr0). They present short (five or six minute) videos featuring researchers describing their research to a general (non-expert) audience. Their tag line is “Outstanding research in everyday language”, and I think the first two installments …

More

Model Credibility

Someone asked an interesting question on a support forum recently. The gist was: “How do I confirm that my model is correct?” On the occasions that I taught simulation modeling, this was a standard topic. Looking back, I don’t recall spending nearly as much time on it when teaching optimization, which was a mistake on …

More

Optimization Pro and Con

A tweet by Nate Brixius (@natebrix) led me to read the article “The Natural Order and Divine Order of Optimization” published by the Wisconsin Institute for Discovery, a rebuttal/counterpoint to a New York Times Magazine article titled “A Sucker is Optimized Every Minute“. The former sings the praises of optimization (somewhat) and the latter vilifies …

More

Partitioning with Binary Variables

Armed with the contents of my last two posts (“The Geometry of a Linear Program“, “Branching Partitions the Feasible Region“), I think I’m ready to get to the question that motivated all this. Let me quickly enumerate a few key take-aways from those posts: The branch and bound method for solving an integer linear program …

More

OR in an OB World

Not infrequently, I am asked about my academic specialty. When I reply “operations research”, as I usually do, I’m often met with a polite but blank stare. This happened to me a couple of times at a recent party. If the questioner inquires further, I’ll try to give an example or two of what OR …

More

Scheduling Instability

Fellow OR blogger Laura McLay recently wrote a post “in defense of model simplicity“, which is definitely worth the read. It contains a slew of links to related material. As I read it, though, my contrarian nature had me thinking “yes … as long as the model is not too simple”. A recent piece in …

More

Fewer Zeros

A question I saw online not too long ago caused me a flashback to my days teaching linear programming (LP) to masters students. The poster had developed an optimization model — I can’t recall if it was an LP, a quadratic program (QP) or a mixed-integer program (MIP) — and had no problem solving it. …

More