Pato’s Game Theory Christmas

The tale of how a college engineering professor once used game theory to turn his holiday gift-giving into an experiment—complete with winners and losers.

By Andrew Egan

Hey all, Ernie here with a piece from Andrew Egan that may be the best application of The Prisoner’s Dilemma to holiday shopping that I’ve seen yet. May the odds be forever in your favor.

Today in Tedium: I love Tedium and I love what it pushes me to do. On my own, I trend to absurdity. This site keeps pushing me to do the wonderfully asinine. The stories I’ve written for Tedium tend to be obscure, ridiculous, and extreme. The story that follows is all of the above. Today’s Tedium hopes you have a happy holiday season while giving you a tale only that could only come from an economist and engineer with a sense of humor. — Andrew @ Tedium

Tedium on Patreon

Keep Us Moving! Tedium takes a lot of time to work on and snark wise about. If you want to help us out, we have a Patreon page where you can donate. Keep the issues coming!

We accept advertising, too! Check out this page to learn more.


The amount of money, in billions, that British grandparents spend on Christmas gifts for their grandchildren, according to a 2017 study by research firm Saga. The study also noted that the average grandparent has three grandchildren and spends an average of $82 on gifts for each. One grandfather decided to upend the process of buying Christmas gifts for his grandchildren but decided to do it in a unique way.

Christmas presents


The grandfather that wanted to turn a holiday tradition into something a little more interesting

Almost every family has its quirky characters, unique traditions, and/or one-off experiments that are recounted at every gathering. Whether traumatic or hilariously or seemingly random, the stories and people that come together to make any given family history are bound to be unique.

This brings us to Dr. Alberto Gomez-Rivas, Ph.d. (that’s not a mistake, we’ll explain in a moment). A professor of engineering that has held positions at Georgia Tech and the University of Houston-Downtown, Gomez-Rivas, known as Pato (Spanish for duck) to his grandchildren, is beloved by his family for his sense of humor and astonishing intellect.

Though primarily an engineer by training and professional experience, Pato also obtained a Ph.D. in economics from Rice University, which he seems to have done largely out of interest rather than professional advancement. (As an aside, I’m fairly certain this makes him one of the first Hispanics in the United States to earn two Ph.Ds.) In the process, he became more familiar with a nascent field of economics that would become increasingly important going into the millennium.

It would also be incredibly important to his grandchildren one fateful Christmas in 2006.


The year that Hungarian mathematician John von Neumann released his seminal work On the Theory of Games of Strategy. The paper would help define the field of game theory, which uses math to find the optimal strategies to win various games. One of the most famous examples of game theory strategy is the prisoner’s dilemma, which seeks to minimize the prison sentences for two hypothetical thieves that are about to be charged with a crime. The ideal solution has both prisoners refuse to cooperate, resulting in no prison time for either.

Shopping mall

A shopping mall, much like the one where the story took place. (stevepb/Pixabay)

One of the rare Christmas stories that involve math, sibling rivalry, and presents

Today, Alberto Gomez-Rivas has a total of six grandchildren ranging in ages from two to 36 years old. A few days before Christmas 2006, he decided it was time to buy gifts for his three oldest grandchildren. So he decided to bring them along to buy their own gifts. However, the professor had an idea.

“I wanted to see if I could spend less on Christmas gifts while still getting [everyone] what they wanted,” Gomez-Rivas said.

The rules of Pato’s game were simple. Each grandchild can buy their own gift, anything they wanted from the sprawling Memorial City Mall. The catch was that there is a budget that he refused to divulge. If just one person uses the whole budget, then the others get nothing. Then, he stepped back and let the kids make their choices.

Needless to say, the kids were at a loss of what to do. Siblings, especially those close in age, are going to be somewhat competitive. This particular group of siblings is somewhat close in age, somewhat competitive, and generally, do like another. No one wanted the others to go without but they still wanted to get the best present possible.

After wandering around the mall for nearly 30 minutes, completely uncertain of what to do, one of them decided to make a move. The second oldest grandchild (who I’ll call grandkid two for now) made his way to the Target store to buy an MP3 player. A slightly pretentious 20-year old who detests Apple products, grandkid two decided to buy a Logitech MP3 player that was more readily compatible with his computer. Total cost: approximately $90.

From here, the rest of the experiment moved pretty quickly. The youngest, 18-year old grandkid three, decided to go next. He headed to the Apple store to buy an iPod Nano that had just been released the previous year. At $150, this brought the total to a relatively modest $240 on gifts so far.

Like many games, the person with the last move is often in a position to win it all. It was no different this time. Grandkid one, the oldest at 25 years old, had been watching her brothers carefully. When it finally came to her turn, she did the math and realized there was no way that Pato’s Christmas budget was only $240, and figured it would be much higher. And since there was no one left to make a move, she decided to test the limit.

Grandkid one headed to Juicy Couture and asked for a pair of sunglasses. The cost? $350. Much to the shock of her younger brothers, Pato gave her the go ahead. Undoubtedly the big winner of Pato’s Game Theory Christmas, her gift cost a $100 more than both her siblings’ gifts combined.

But hey, it could always be worse

If you want interesting or funny stories about Christmas, look no further than the ridiculous anecdotes submitted by people to Reader’s Digest. The small, legacy publication has long published jokes and stories submitted by its readers but the submissions hit overdrive around Christmas time. It seems like everyone has their own weird and funny Christmas stories. Here’s a quick look at some of the funniest, or worst, depending on your perspective:

”One year, my father gave Mom a DVD. In and of itself it wasn’t a bad gift, except a) it was a rental, and b) we didn’t own a DVD player.”

”Securing Christmas lights to the tree can be a production. One year, when we finally stood back and flicked on the light switch, I noticed that a branch obscured our prized angel ornament. I grabbed the pruning shears, mounted a stool, and snipped once, and the lights went out. My husband quietly said, ‘You don’t have your glasses on, do you?’”

”My ex-boyfriend used to call me ‘Larry’ as a joke instead of ‘Perri.’ For the holidays one year, he gave me a Tiffany’s robin’s-egg blue box. Exciting! Inside, I found a beautiful, initial necklace…but an ‘L,’ for Larry. I tried wearing it, but it was too hard to explain why the pricey jewelry had the wrong letter. To this day, I’m still in search of a best friend whose name starts with an L so I can pass it along.”

If the story seems a little cruel, don’t worry about it. Though it would be easy to complain about the cost disparity between the gifts, each kid was happy with their respective choices. Grandkid two was still using his MP3 player long after the Juicy glasses went out of style. Grandkid three still has his Nano in a drawer at their parent’s house.

The experience was definitely a unique one that stuck with each of the grandkids as they made their way into and out of college and beyond. Grandkid one would go onto become a special education math teacher and administrator. Grandkid two would later take numerous game theory classes on his way to a degree in political science, while Grandkid three would end up as a consultant for mega-firm Deloitte.

Sharing intimate family stories to a larger public always come at some risk as interpretation is incredibly subjective. But the three grandchildren that played Pato’s Game Theory Christmas don’t have regrets or animosity toward their wonderfully eccentric grandfather. It’s all part of his charm.

And I can say all of this confidently—because I was the idiot child that went first.

Andrew Egan

Your time was just wasted by Andrew Egan

Andrew Egan is yet another writer living in New York City. He’s previously written for Forbes Magazine and ABC News. You can find his terrible website at

Find me on: Website