27/09/2018

Science & Math Blog: The So-Called Algorithm

Reproduction from the IMPA Science & Mathematics blog, from O Globo, coordinated by Claudio Landim.

Roberto Imbuzeiro Oliveira – Senior Researcher at IMPA

Last year, IMPA organized an event for schools as part of the National Science and Technology Week. Using this as a pretext, Rádio Nacional invited me to talk about the event and mathematics in general.

The journalist conducting the interview told me a story. A few days earlier, she had helped her daughter look for an apartment. After that, she started noticing many real estate ads on Facebook. We all agreed that this is a common phenomenon, which makes us uncomfortable. But then the interviewer asked…

– That's what they call an algorithm, right, professor?

The purpose of this article, then, is to explain who "this algorithm" is and what its role is in this case and in all other similar cases.

Who is this algorithm?

First, let's try to understand what an algorithm actually is. Behind the "magic" or "spying" of Facebook, there is something that, fundamentally, is very simple and present throughout computing.

An algorithm is nothing more than a sequence of "precise" instructions to perform a task. When I say "precise," I mean instructions that leave no room for doubt or interpretation and that always lead to the same results. In other words, I'm talking about something like the rules for performing arithmetic operations in school.

It is no coincidence that the history of algorithms is, first and foremost, a piece of the history of mathematics. Although rules for tasks and operations have existed for a long time, Euclid's algorithm for division is the oldest to truly live up to its name. If even today there are those who struggle with division, it is not Euclid's fault: he established the correct rules; it is up to us to execute them accurately.

The word "algorithm" only emerged in the Middle Ages. It comes from the name of the Persian Muhammad ibn Musa al-Khwarizmi, who was an astronomer at the House of Wisdom of the Abbasid Caliphate in Baghdad. Thanks to his vast work, the Indo-Arabic numeral system, which we use to this day, spread throughout the Middle East and the West. The name "al-Khwarizmi," duly Latinized, was first associated with the numeral system and later with the modern concept of algorithm.

Algorithms and Computers

Over the years, the idea of an algorithm has taken new directions. A major conceptual leap was the realization that a "perfect recipe" could be executed not only by humans, but also by machines. This is precisely the idea behind a computer: to create devices capable of executing algorithms, whether for calculations, processing text and images, or anything else that computers do.

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