Category Archives: Teaching

Bringing Research into the Classroom: Can Relevant and Impactful be Easy to Explain?

math-equation_chalkboard O.R. researchers and practitioners are constantly churning out papers that tackle a wide variety of important and hard-to-solve practical problems. On one hand, as a researcher, I understand how difficult these problems can be and how it’s often the case that fancy math and complex algorithms need to be used. On the other hand, as someone who teaches optimization to MBA students who aren’t easily excited by mathematics, I’m always looking for motivational examples that are both interesting and not too complex to be understood in 5 minutes. (That’s the little slot of time I reserve at the beginning of my lectures to go over an application before the lecture itself starts.)

Every now and then, I come across a paper that fits the bill perfectly: it addresses an important problem, produces impactful results, and (here comes the rare part), accomplishes the previous two goals by using math that my MBA students can follow 100%, while being confident that they themselves could replicate it given what they learned in my course (the optimization models).

The paper to which I’m referring has recently appeared in Operations Research (Articles in Advance, January 2017): The Impact of Linear Optimization on Promotion Planning, by Maxime C. Cohen, Ngai-Hang Zachary Leung, Kiran Panchamgam, Georgia Perakis, and Anthony Smith (http://dx.doi.org/10.1287/opre.2016.1573).

If I had to pick one word to describe this paper, it would be BEAUTIFUL.

I immediately proceeded to put together a 5-minute summary presentation (8 slides) to cover the problem, approach, and results. I’ll be showing this to 100 of my MBA students on this coming Tuesday (Valentine’s Day!). I hope they love it as much as I did. Feel free to show this presentation to your own students if you wish, and let me know how it went down in the comments.

A recent Poets & Quants article explains how business schools with the highest quality teaching strive to bring their faculty’s research into the classroom so that students get to learn the latest and greatest ideas. The O.R. paper above is a perfect example of when this can be done effectively.

1 Comment

Filed under Analytics, Applications, Integer Programming, Linear Programming, Modeling, Motivation, Promoting OR, Research, Teaching

Portuguese Pronunciation and Language Tips

I’ll be taking a group of 34 MBA students on an international business immersion trip to my native Brazil this Spring. We’ll be visiting about a dozen companies in the cities of São Paulo and Rio de Janeiro. This is an initiative created by the awesome Center for International Business Education and Research (CIBER) at the University of Miami.

I’d like my students to be able to pronounce some of the main sounds in Portuguese correctly because I know Brazilians pay attention and really enjoy when foreigners make an effort to say things properly. Therefore, I created a video in which I go over what I consider to be some of the most important things to know when speaking Portuguese (there are others, but I didn’t want the video to be too long).

You can access it on my YouTube channel here: https://www.youtube.com/watch?v=LzgoYFokBPk

Moreover, the 2016 Olympic Games are coming, so I figured these tips could be useful for a larger audience as well. I wish American sports casters would watch this video because they murdered the pronunciation of everything during the World Cup in 2014.

Bonus material: My daughter, Lavinia Lilith, a.k.a. #LLCoolBaby, makes a short appearance at around the halfway mark.

Enjoy!

Leave a comment

Filed under Brazil, People, Teaching, Tips and Tricks, Travel, Videos, YouTube

Improving a Homework Problem from Ragsdale’s Textbook

UPDATE (1/15/2013): Cliff Ragsdale was kind enough to include the modification I describe below in the 7th edition of his book (it’s now problem 32 in Chapter 6). He even named a character after me! Thanks, Cliff!

When I teach the OR class to MBA students, I adopt Cliff Ragsdale’s textbook entitled “Spreadsheet Modeling and Decision Analysis“, which is now in its sixth edition. I like this book and I’m used to teaching with it. In addition, it has a large and diverse collection of interesting exercises/problems that I use both as homework problems and as inspiration for exam questions.

One of my favorite problems to assign as homework is problem number 30 in the Integer Linear Programming chapter (Chapter 6). (This number refers to the 6th edition of the book; in the 5th edition it’s problem number 29, and in the 4th edition it’s problem number 26.) Here’s the statement:

The emergency services coordinator of Clarke County is interested in locating the county’s two ambulances to maximize the number of residents that can be reached within four minutes in emergency situations. The county is divided into five regions, and the average times required to travel from one region to the next are summarized in the following table:

The population in regions 1, 2, 3, 4, and 5 are estimated as 45,000,  65,000,  28,000,  52,000, and 43,000, respectively. In which two regions should the ambulances be placed?

I love this problem. It exercises important concepts and unearths many misconceptions. It’s challenging, but not impossible, and it forces students to think about connecting distinct—albeit related—sets of variables; a common omission in models created by novice modelers. BUT, in its present form, in my humble opinion, it falls short of the masterpiece it can be. There are two main issues with the current version of this problem (think about it for a while and you’ll see what I mean):

  1. It’s easy for students to eyeball an optimal solution. So they come back to my office and say: “I don’t know what the point of this problem is; the answer is obviously equal to …” Many of them don’t even try to create a math model.
  2. Even if you model it incorrectly, that is, by choosing the wrong variables which will end up double-counting the number of people covered by the ambulances, the solution that you get is still equal to the correct solution. So when I take points off for the incorrect model, the students come back and say “But I got the right answer!”

After a few years of facing these issues, I decided I had had enough. So I changed the problem data to achieve the following (“evil”) goals:

  1. It’s not as easy to eyeball an optimal solution as it was before.
  2. If you write a model assuming every region has to be covered (which is not a requirement to begin with), you’ll get an infeasible model. In the original case, this doesn’t happen. I didn’t like that because this isn’t an explicit assumption and many students would add it in.
  3. If you pick the wrong set of variables and double-count the number of people covered, you’ll end up with an incorrect (sub-optimal) solution.

These improvements are obtained by adding a sixth region, changing the table of distances, and changing the population numbers as follows:

The new population numbers (in 1000’s) for regions 1 through 6 are, respectively, 21, 35, 15, 60, 20, and 37.

I am now much happier with this problem and my students are getting a lot more out of it (I think). At least I can tell you one thing: they’re spending a lot more time thinking about it and asking me intelligent questions. Isn’t that the whole purpose of homework? Maybe they hate me a bit more now, but I don’t mind practicing some tough love.

Feel free to use my modification if you wish. I’d love to see it included in the 7th edition of Cliff’s book.

Note to instructors: if you want to have the solution to the new version of the problem, including the Excel model, just drop me a line: tallys at miami dot edu.

Note to students: to preserve the usefulness of this problem, I cannot provide you with the solution, but if you become an MBA student at the University of Miami, I’ll give you some hints.

7 Comments

Filed under Books, Integer Programming, Modeling, Teaching

MLB Umpire Scheduling

There are two purposes to this post. First, I’d like to follow-up on Michael Trick’s post on the importance of teaching and its relationship with research. One of the points Mike makes is that your next exciting research or consulting project may come from current or former students. Those of us who teach undergraduate and MBA classes have the opportunity to network with (future) managers and practitioners who will eventually put their training to the test, producing actual answers to real-life problems. And if one of those problems requires more OR knowledge than what they had the opportunity to learn in school, they might remember their friendly neighborhood OR professor. Another way research can come out of teaching is during hands-on projects. Back in 2006, Mike was in charge of an elective OR-project class that allows MBA students to try their hands on a real-life problem; in that case umpire scheduling. To my delight, Mike invited me to be the TA for that course and I gladly accepted. The rest is history.

The second purpose of this post is to help myself keep track of the recent news stories about our umpire scheduling paper. Thanks to an excellent job by the PR departments at the University of Miami School of Business (thanks, Catharine!) and Michigan State University, the story has appeared in numerous outlets. As a matter of fact, I’m very excited to report that Scientific American had a 60-second science podcast about our work:

August 18Scientific American: Researchers Tell Umpires Where to Go (PDF version)

Here are a few other news outlets that covered the story (I’m trying to keep this list up-to-date for my own sake). I’m also providing a link to a PDF version of each story in case the web pages are taken offline:

April 2012, The Spring issue of Business Miami Magazine has an article about our work entitled Road Trip (PDF version).

October 19, WAMC Northeast Public Radio Academic Minute. I recorded a 1:45-minute explanation of the problem, approach, and results which aired as one of WAMC’s Academic Minutes on the same day of the first game of the World Series. That was a lot of fun! Click on the link to listen. If the link doesn’t work, here’s the MP3 file.

September 6, Miami New Times: Tallys Yunes, UM Professor, Solves MLB’s Umpire Scheduling Dilemma (PDF version). This article also appeared in print, in the September 8-14 issue of Miami New Times. Here’s a PDF scan of that.

August 3, PhysOrg: University of Miami Business Professor Helps Create a Successful Scheduling Method for Umpires in Major League Baseball (PDF version)

August 3, HPCwire: Business Prof Solves Traveling Umpire Problem for Major League Baseball (PDF version)

July 31, University of Miami School of Business: School’s Management Science Research Resolves Major League Baseball’s Umpire Scheduling Challenges (PDF version)

July 21, ScienceDaily: Scholar Helps Make Major League Baseball Umpire Schedule a Hit (PDF version)

July 21, ThePostGame: MLB Umpires Have a Turkish Secret Weapon (PDF version)

July 20, PhysOrg: Michigan State Scholar Helps Make MLB Umpire Schedule a Hit (PDF version)

July 20, Michigan State University News: Michigan State Scholar Helps Make MLB Umpire Schedule a Hit (PDF version)

I greatly enjoy the teaching side of my job because I believe it complements the research side quite well. I’m looking forward to bringing articles like the ones above to my classes in the Spring and I’m sure they’ll be well received.

Further acknowledgments: thanks to those who also helped spread the word about the umpire scheduling problem on Twitter, especially Paul Rubin (@parubin), Aurélie Thiele (@aureliethiele), and @INFORMS (is that you, Mary Leszczynski? :-).

3 Comments

Filed under Applications, Heuristics, Promoting OR, Research, Sports, Teaching, Traveling Umpire Problem

Big Bang Theory Party Planning

Penny is organizing a party at her apartment, but she is on a tight budget. Having a working knowledge of all of the important things in the universe, Sheldon knows everything about linear programming and offered to help her. He postulates that it’s ideal to have two kinds of mixed nuts: a plain party mix, and a luxury mix (for those with a distinct taste like himself). Based on the expected number of guests, Howard quickly calculates that they’ll need a total of at least 10 pounds of snacks, but no more than 6 pounds of each kind of mix. On his white board, Sheldon has already come up with the following table:

Raj wants to dip the hazelnuts into liquor, but that’s not in the budget, so he gives up. Leonard reminds everyone that, because of their allergies, it’s important to keep the average allergenicity level per pound in both mixes to no more than 3. Write an optimization model to help Penny prepare the two kinds of snacks at minimum cost. But be careful: Sheldon will check it later for correctness!

This post is part of my series “Having Fun with Exam Questions”. Previous questions dealt with Farmville, vampires, and (potentially) Valentine’s day.

1 Comment

Filed under Big Bang Theory, Exam Fun, Linear Programming, Modeling, Teaching

An OR Song: Math’s in Hiding

One of my goals with this blog is to help spread the word about the fabulous field of Operations Research (OR). I’m saddened, however, by how much the average person still hates mathematics and sees it as being of no use outside the classroom. Popular movies and TV shows (with very few exceptions) don’t portray math positively either (see, for example, this post by my former Carnegie Mellon classmate Abraham Flaxman).

Why do most people think it’s OK to hate math? I bet that if someone came on TV and said “I hate History” it would be a big deal, and critics would promptly jump in to provide explanations about the merits of the field. But hating math is commonplace; it’s “normal”. I beg to differ. I believe that it’s just a matter of teaching it differently and showing students, from the very beginning, all the wonderful things that math can accomplish. This is a crucial change that needs to begin in high school (if not earlier).

So I decided to write a song. More precisely, I decided to write alternative lyrics for an existing song. After all, everyone likes music, right? The song I chose to hijack was “Hallelujah”, written by Leonard Cohen in the 80’s. It’s a beautiful song that has been recorded by many different artists, the late Jeff Buckley being among the most popular ones (here’s a YouTube video). Personally, I prefer Allison Crowe’s interpretation because it’s a little more dramatic.

Before I show you the lyrics, a few comments are in order:

  • Although the song is about OR, I use the word “math” throughout because it is a more recognizable word. Besides, OR is about using math to improve decision making, and part of my goal is to help people realize that (there’s a shout out to INFORMS at the end :-)
  • I decided to refer to math as “she” because (i) it creates a parallel to the “she” in the original lyrics; (ii) this kind of anthropomorphism has been used before; (iii) it sounds more melodic and poetic than using “it”. However, if you are offended by that, or think this is politically incorrect, just replace “she/her” with “it/its”.
  • I’ve put the original Hallelujah lyrics side-by-side with my lyrics to make it easier for you to sing it. I chose the words carefully so that the cadence/tempo would remain the same. Trust me. I’ve tried it myself and it works.
  • I only have the lyrics so far (no recording) because I’m not a good singer, and I haven’t found anyone to sing it yet. I’d like to have a YouTube video clip with the lyrics as subtitles and a photo slide show, in sync with lyrics, showing examples of OR success stories.
  • I’ve included a few footnote questions about subtle references that appear in the lyrics (OK, I admit, most of them are easy). I figured it would be a fun little quiz anyway. If you know the answers, write them down in the comments below.

So, without further ado, here it is: Math’s in Hiding. Enjoy! And let me know what you think. I’d love to hear your thoughts!

Going back to the topic of who could record this: ideally it should be someone who is familiar with OR. Well, I just happen to know the perfect person. Her name is Lucia. In addition to being a very talented singer and song writer (her debut album was released last year and she recently sang the national anthem at a Marlins game), she was my student in the MBA Optimization class a few years ago. Wouldn’t it be great to have an OR-themed concert at an INFORMS meeting with free tickets distributed to the general public?

Regardless of whether my lyrics are good or bad, I believe that songs like this are another way for us to try to plant the seed of love-for-math in the heart of future generations. At least it’s worth a try.

6 Comments

Filed under Motivation, Music, Promoting OR, Teaching

Beautiful and Useful Scale of the Universe

Thanks to my former MBA student Max Marty, I came across this interactive scale of the universe (click on the word “Play” below the video game ad). It’s easy to lose track of how big 10^10 is, and this scale helps to put things in perspective. Next time you’re teaching a course in optimization or constraint satisfaction and you tell your students a certain problem has 10^100 possible solutions, bring this scale up on the screen! (Tip from the creators: it’s better to use the arrow keys rather than the mouse to scroll left and right.)

Leave a comment

Filed under Scale, Teaching