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Proofs From The Book
April’s Book of the Month is Proofs From The Book by Martin Aigner and Günter Zeigler. (The first edition came out in 1998 — note the new editions) From the preface to the first edition. Paul Erdös liked to talk … Continue reading
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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
Banach’s microscope to find a fixed point
Originating author is Christiane Rousseau. In this vignette, we will show how we start from a small game to discover one of the most powerful theorems of mathematics, namely the Banach fixed point theorem. This theorem has fantastic applications inside … Continue reading
What is the way of packing oranges? — Kepler’s conjecture on the packing of spheres
Originating author is Christiane Rousseau. What is the densest packing of spheres? Kepler conjectured that it was the one you observe with oranges at the fruit shop, and which is called the face-centered cubic lattice (Figure 1). At the International … Continue reading