Coordinating Variable Signs

Someone asked me today (or yesterday, depending on whose time zone you go by) how to force a group of variables in an optimization model to take the same sign (all nonpositive or all nonnegative). Assuming that all the variables are bounded, you just need one new binary variable and a few constraints. Assume that …

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A Few Reflections on the TOME Initiative

WASHINGTON, DC – Today a group of colleagues from the Association of American Universities, Association of Research Libraries, and Association of University Presses met to advance the Towards an Open Monograph Ecosystem (TOME) initiative. It was heartening to see the progress the initiative has made since our first gathering in the summer of 2016. At the time, I was enthusiastic …

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Selecting Box Sizes

Someone posted an interesting question about box sizes on Mathematics Stack Exchange. He (well, his girlfriend to be precise) has a set of historical documents that need to be preserved in boxes (apparently using a separate box for each document). He wants to find a solution that minimizes the total surface area of the boxes …

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Evolution of a (data) visualization

Last summer, I taught the MAET Year 2 Summer Cohort with Danah Henriksen. After teaching the class, Danah realized she had taught five cohorts of (awesome) students and that we had some information available from pre- and post-course self-reported surveys to understand how students grew in terms of their confidence in using different educational (and …

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Callback Cuts That Repeat

The following post is specific to the CPLEX integer programming solver. I have no idea whether it applies to other solvers, or even which other solver have cut callbacks. Every so often, a user will discover that a callback routine they wrote has “rediscovered” a cut it previously generated. This can be a bit concerning …

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Grouping Rows of a Matrix

I spent a large chunk of yesterday afternoon doing something I thought would be simple (relatively speaking) in LaTeX. I wanted to group rows of a matrix (actually, in my case, a vector) with right braces, and label the groups. An example of what I wanted is in the image below. This seems to me …

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Big M and Integrality Tolerance

A change I made to an answer I posted on OR-Exchange, based on a comment from a well-informed user of OR-X, might be worth repeating here on the blog. It has to do with issues that can occur when using “big M” type integer programming models, a topic I’ve covered here before. As I mentioned …

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Cultivating a Culture of Trust

It has been difficult to write for the public in the months since posting the Open Letter to the College of Arts & Letters in the wake of the survivor impact statements that are transforming Michigan State University.1 Part of the difficulty is what my thoughtful #SpartanDean colleague, Prabu David, emphasized when he wrote that it is challenging to find the right …

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Stephen Hawking (1942-2018)

Roger Penrose writes in the Guardian, providing a scientifically precise summary of Hawking’s accomplishments as a physicist (worth reading in full at the link). Penrose and Hawking collaborated to produce important singularity theorems in general relativity in the late 1960s. Here is a nice BBC feature: A Brief History of Stephen Hawking. The photo above …

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How NSA Tracks You (Bill Binney)

Anyone who is paying attention knows that the Obama FBI/DOJ used massive government surveillance powers against the Trump team during and after the election. A FISA warrant on Carter Page (and Manafort and others?) was likely used to mine stored communications of other Trump team members. Hundreds of “mysterious” unmasking requests by Susan Rice, Samantha …

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National Indian Law Library Bulletin (2/22/2018)

Here: The National Indian Law Library added new content to the Indian Law Bulletins on 2/22/18. U.S. Supreme Court Bulletin http://www.narf.org/nill/bulletins/sct/2017-2018update.html Petition for certiorari was denied in Renteria, et al. v. Superior Court of California, Tulare County, et al. (Indian Child Welfare Act) and in Norton, et al. v. Ute Indian Tribe of the Uintah and Ouray Reservation, et …

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Documentary Films as Soccer Storytelling

I recently went on a cinematic journey that took me from women’s soccer in Zanzibar to a failed stadium-and-entertainment complex in Buenos Aires. My travel agency, so to speak, was the Football Scholars Forum. On February 23 it held an online discussion of two low-budget, high-return documentary films. (A recording of the event can be found here. …

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A Compass for the Future

Michigan State University (MSU) is making national and international news. And it’s not for its prowess on athletic fields or courts. In fact, as I’m sure everyone reading this is aware, it is for the tragedy of sexual abuse that went on for years without being stopped. The president is gone, the gymnastics coach is …

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A Transformative Moment

While I have been retired from Michigan State University for three years, I spent 30 years of my life walking the campus, teaching classes, helping students and faculty uncover information they sought, active in faculty governance and founding and directing sustainability operations. It is no small part of my life. So it is not without …

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A Shiny interactive web application to quantify how robust inferences are to potential sources of bias (sensitivity analysis)

We are happy to announce the release of an interactive web application, Konfound-It, to make it easy to quantify the conditions necessary to change an inference. For example, Konfound-It generates statements such as “XX% of the estimate would have to be due to bias to invalidate the inference” or “an omitted variable would have to …

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Outcomes from a self-generated utility value intervention in science (in IJER)

The Scientific Practices project, was focused on engaging middle school students in scientific and engineering practices (such as developing and using models, constructing explanations of phenomena, and analyzing and interpreting data). As part of this longitudinal project, we carried out field experiments to understand the impact of specific features of the curriculum. In this paper published …

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Beware the Jabberwocks

Lessons from the Dragon Boat None of us knew quite what to expect on Saturday as we gathered at Hawk Island for our one-hour training session for the Capital City Dragon Boat Race to support the Women’s Resource Center of Greater Lansing. Earlier this year, my wife, Val, suggested that the MSU College of Arts & …

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Step Acuity

Please help me with a little science experiment. Measure your Step Acuity (SA) and report it here. Your SA is the number of steps before you hit a mark that you know whether you will hit the mark with your right or left foot. As you are walking down the street, choose a mark (a …

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Heroes

Heroes play a crucial role by showing us what we, individually and collectively, can accomplish and demonstrating that we can do great things despite long odds. Heroes play a crucial role by showing us what we, individually and collectively, can accomplish and demonstrating that we can do great things despite long odds. For many Americans …

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Varieties of Time Travel

My kids have been reading lots of books over the break, including an adventure series that involves time travel. Knowing vaguely that dad is a theoretical physicist, they asked me how time travel works. 1. Can one change history by influencing past events? OR 2. Is there only one timeline that cannot be altered, even …

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Time and Memory

Over the holiday I started digging through my mom’s old albums and boxes of photos. I found some pictures I didn’t know existed! Richard Feynman and the 19 year old me at my Caltech graduation: With my mom that morning — hung-over, but very happy! I think those are some crazy old school Ray Bans …

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2016 (on two wheels)

2016 (on two wheels) was a good year with some challenging points too. Here were some rides silly, challenging, and otherwise memorable: This was one of the most strange rides ever. Katie and I decided to head to St. John’s. It doesn’t look too far (from where we are in Lansing), and it’s not, but …

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Matt Townsend Show (Sirius XM)

I was on this show last week. Click the link for audio. We Are Nowhere Close to the Limits of Athletic Performance (16:46) Dr. Stephen Hsu is the vice president for research and a professor of theoretical physics at Michigan State University. His interest range from theoretical physics and cosmology to computer science and biology. …

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Time to Break Silence

  Well I haven’t exactly been silent in recent years, but I think the circumstances we are in call for being unafraid to stand up to forces that are dragging us toward our collective demise, but also to offer alternatives that redirect us towards a more just and peaceful future. It will be 50 years …

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