Wikimedia Commons
Wikimedia Commons

Edsger Dijkstra, Computer Scientist

Wikimedia Commons
Wikimedia Commons

In our Retrobituaries series, we highlight interesting people who are no longer with us. Today let's explore the life of Edsger Dijkstra, who died at 72 in 2002. 

If you’ve used a computer or smart phone in the last few decades, you’ve come into contact with the work of Edsger Dijkstra. Since his death in 2002, his research in the field of computer science has in many ways only grown more important. Here are a few things you didn’t know about his life and his science. 

If you took his computer science class, you probably didn’t touch a computer.

Professor Dijkstra once said, “Computer science is no more about computers than astronomy is about telescopes,” and he taught his courses accordingly. He was a proponent of elegance in mathematical proofs, whereby puzzles are solved with efficiency and aesthetic sensitivity.

Grades were determined by the final exam, which was neither written on a piece of paper nor typed on a computer. Rather, students were given individual oral examinations in his office or at his home. The conversational exams lasted hours at a time, and students were asked how they might prove various mathematical propositions. They were then challenged to write out their proofs on a chalkboard. After the exam, students were offered a beer if they were of age, or a cup of tea, if they were not. 

He didn’t use email. Or a word processor.

Dijkstra was famous for his general rejection of personal computers. Instead of typing papers out using a word processor, he printed everything in longhand. He wrote well over a thousand essays of significant length this way, and for most of his academic career, they proliferated by ditto machine and fax. Each essay was given a number and prefixed with his initials, EWD.

Students who emailed Dijkstra were asked to include a physical mailing address in the letter. His secretary would print the message, and he would respond by hand.

Computers weren’t the only technology he shunned. He refused to use overhead projectors, calling them “the poison of the educational process.”


Use Google Maps? You can thank Dijkstra.

Among his profound contributions to computer science is a solution to the “single source shortest-path problem.” The solution, generally referred to as Dijkstra’s algorithm, calculates the shortest distance between a source node and a destination node on a graph. (Here is a visual representation.) The upshot is that if you’ve ever used Google Maps, you’re using a derivation of Dijkstra’s algorithm. Similarly, the algorithm is used for communications networks and airline flight plans. 

He “owned” a nonexistent company.

In many of his more humorous essays, he described a fictional company of which he served as chairman. The company was called Mathematics, Inc., and sold mathematical theorems and their maintenance. Among the company’s greatest triumphs was proving the Riemann hypothesis (which it renamed the Mathematics, Inc. Theorem), and then it unsuccessfully attempted to collect royalties on all uses of the mathematical conjecture in the real world. Evidence was never given of the proof, of course, because it was a trade secret. Mathematics Inc. claimed to have a global market share of 75 percent.

He was the first programmer in the Netherlands.

In the 1950s, his father suggested that he attend a Cambridge course on programming an Electronic Delay Storage Automatic Calculator, or EDSAC. Dijkstra did, believing that theoretical physics (which he was studying at the time at Leiden University) might one day rely upon computers. The following year, he was offered a job at Mathematisch Centrum in Amsterdam, making him the first person in the Netherlands to be employed as something called a “programmer.” (“A programmer?” he recalled of the moment he was offered the position. “But was that a respectable profession? For after all, what was programming? Where was the sound body of knowledge that could support it as an intellectually respectable discipline?” He was then challenged by his eventual employer to make it a respectable discipline.) 

This would later cause problems. On his marriage application in 1957, he was required to list his profession. Officials rejected his answer—”Programmer”—stating that there was no such job.

Previously on Retrobituaries: Albert Ellis, Pioneering Psychologist. See all Retrobituaries here.

Prepare to Be Stumped By This Math Problem Meant for Fifth Graders

Math is hard. Just ask Mumsnet user PeerieBreeks, who posted a ‘simple’ math riddle meant for fifth graders to the parenting website, and ended up with more than 500 comments—many of them from adults struggling to come up with the correct answer. Here’s the riddle:

For the most part, the problem-solvers who shared their answers all believed that the man made a profit, but whether it was $10, $20, or $30 seemed to be in hot dispute. Can you figure it out? (Scroll down for the answer. We’ll give you a minute …)






The wording of the riddle, not the math, seems to be what’s throwing most people off. Because the transactions in question relate to the same horse, people are looking at it as a single, four-part transaction—buys, sells, buys, sells. But the correct way to look at the problem, and figure out the answer, is to look at it as just two transactions: a man bought a horse and sold a horse. A man bought a horse and sold a horse. (The man could just as easily have bought and sold a dog in one of those transactions and it wouldn’t change the outcome.)

All of which is to say that the correct answer is: The man made a $20 profit.

15 Pi Day Gifts for the Math Fan in Your Life

March 14, the mathematic high holiday known as Pi Day, is right around the corner. To celebrate everyone's favorite irrational number, we've rounded up some gifts to help the math aficionados in your life—the ones who know that pi is the ratio of the circumference of a circle to its diameter—observe Pi Day in proper fashion.

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1. PI PIE PAN; $25

If Pi Day passed and you didn't eat a pi pie, did Pi Day even happen? This specially shaped baking pan makes the equivalent volume of a 9-inch round pan, but obviously has more surface area than a standard pan. Pi puns and extra crust? Sounds like a win-win dessert.

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Pair that pi pie with a set of these special plates decorated with a formula that spells out "imaginary unit eight summation pi"—or, essentially, "I ate some pie." Yes please!

Find It: Uncommon Goods


Inspire a love of irrational numbers in the young mathematician-to-be in your life with this adorable cotton onesie, available in five colors for 6-24 month olds.

Find It: Etsy


We do our best thinking in the shower, and this machine-washable shower curtain is sure to inspire a stumped mathematician to finally figure out x once and for all.

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Consider this equation: Math puns + affordability = this hilarious gift tee.

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You'll be toasting to a gift well done after they open this set of four pint glasses measuring out the number of ounces in Pythagoras's constant, the Golden Ratio, Euler's Number, and of course pi.

Find It: Uncommon Goods


It's never too early to get your budding mathematician hooked on STEM! This quantum physics intro is meant for 1–3 year olds, but it's a good refresher for adults to brush up on their knowledge too.

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This "classroom pack" of temporary tattoos means that when you and 44 of your closest pi pals practice memorizing pi's numerous digits, you never have to leave home without your cheat sheet.

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Definitely know your audience before gifting this head-scratcher of a clock. For some, the regular mental exercise to figure out the time would be a welcomed brain-teaser. For others, it could be a frustrating distraction. But, we think its namesake—it should be relatively easy to figure out which Albert it's referencing—would be a fan.

Find It: Museum of Modern Art


Spend your savasana meditating on the wonders of math in these equation-covered leggings, which come in sizes XS-4X.

Find It: Modcloth


Ancient calculators make great toys when it comes to this colorful bead toy aimed at kids 2 and up. But once the young ones hit grade school, this specially marked abacus will help them visualize arithmetic while still seeing the equations listed out.

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This coloring book takes nature's best mathematical patterns and turns them into a soothing adult coloring book. Take a break from studying math's interconnected worlds, and just connect pencil to paper for a bit.

Find It: Target


Cookies are certainly easier to bake in bulk than pies. And if our math checks out, that means they will probably last a little longer too …

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This hands-on math game makes learning arithmetic engaging and entertaining, and can help kids 3–6 years old recognize units and solve basic additions and subtractions. These wooden letters come with three free apps that you pair with any iPad and most Samsung and Nexus tablets.

Find It: Target


You saw the movie—now delve even deeper into the true stories of Katherine Johnson, Dorothy Vaughan, Mary Jackson, and the other African-American women who worked at NASA as "human computers" during the Space Race. Margot Lee Shetterly's best-seller reveals just how much ground-breaking work these brilliant mathematicians truly did, even while dealing with both gender discrimination and the Jim Crow era. And if you haven't seen the movie, stream it on HBO or purchase it here.

Find It: Amazon


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