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# Category Archives: Mathematics Within the Last 100 Years

## From synthetic geometry to dynamic geometry and back: the case of circular inversion

by Giulia Signorini, Michele Tocchet, both from “Liceo Filippo Buonarroti” in Pisa, and Anna Baccaglini-Frank, University of Pisa. In 1871 Felix Klein published two papers, called “On the so-called non-Euclidean geometry”, in which he proposed to call the first type … Continue reading

## Contribution of the month: Prizes in mathematics, 2020

by Nitsa Movshovitz-Hadar (Technion – Israel Institute of Technology) Did you know? – Over 125,000 new items are added each year, to the international database managed by the American Mathematical Society called MathSciNet®1 A vast majority of these items contain … Continue reading

## The Enormous Theorem

Originating author is Nitsa Movshovitz-Hadar. Prolog This article is an English translation with emendations of a Hebrew paper written in 2014 about two years after the untimely passing of the illustrious lecturer and group theory expert, Professor David Chillag. It … Continue reading

## How do I Solve this Equation? Look at the Symmetries! – The Idea behind Galois Theory

Originating author is Timo Leuders. Introduction There are some questions that accompany the development of mathematics through cultures and ages. One of these questions is how to find an unknown quantity of which one knows some relations such as – … Continue reading

## Trading in a Town

Originating authors are Alberto A. Pintoa (University of Porto, cLIAAD-INESC Porto LA) and Telmo Parreira (University of Minho, cLIAAD-INESC Porto LA). Have you ever been frustrated by the lack of choices when you go to buy something? Why do producers … Continue reading

## How Google works: Markov chains and eigenvalues

Originating author is Christiane Rousseau. From its very beginning, Google became “the” search engine. This comes from the supremacy of its ranking algorithm: the PageRank algorithm. Indeed, with the enormous quantity of pages on the World-Wide-Web, many searches end up … Continue reading

## Dimension

Originating author is Christiane Rousseau. How do we measure the size of a geometric object? For subsets of the plane we often use perimeter, length, area, diameter, etc. These are not sufficient to describe fractals. The fractal objects are very … Continue reading

## Fair voting: the quest for gold

Originating authors are Gabriel Rosenberg and Mark Iwen. It is a little known fact that two gold medals were awarded for the same pairs figure skating competition in the 2002 Winter Olympics. These two medals were ultimately a result of … Continue reading

## Goodstein Sequences: The Power of a Detour via Infinity

Originating authors are Michèle Artigue, Ferdinando Arzarello and Susanna Epp. Studying the evolution of a natural phenomenon often leads to studying numerical sequences , especially their long-term behavior and whether they eventually converge. Polynomial, exponential, and logarithmic sequences are frequently … Continue reading

## Matrices and Digital Images

Originating authors are Dirce Uesu Pesco and Humberto José Bortolossi. The images you see on internet pages and the photos you take with your mobile phone are examples of digital images. It is possible to represent this kind of image … Continue reading