Geometry and Topology

mathemathical subject image: 

The Willmore Conjecture

The Willmore problem studies which torus has the least amount of bending energy. We explain how to think of a torus as a donut-shaped surface and how the intuitive notion of bending has been studied by mathematics over time. 

Polyhedra and commensurability

This snapshot introduces the notion of commensurability of polyhedra. At its bottom, this concept can be developed from constructions with paper, scissors, and glue. Starting with an elementary example, we formalize it subsequently. Finally, we discuss intrigu- ing connections with other fields of mathematics. 

Das Problem der Kugelpackung

Wie würdest du Tennisbälle oder Orangen stapeln? Oder allgemeiner formuliert: Wie dicht lassen sich identische 3-dimensionale Objekte überschneidungsfrei anordnen? Das Problem, welches auch Anwendungen in der digitalen Kommunikation hat, hört sich einfach an, ist jedoch für Kugeln in höheren Dimensionen noch immer ungelöst. Sogar die Berechnung guter Näherungslösungen ist für die meisten Di- mensionen schwierig. 

From computer algorithms to quantum field theory: an introduction to operads

An operad is an abstract mathematical tool encoding operations on specific mathematical structures. It finds applications in many areas of mathematics and related fields. This snapshot explains the concept of an operad and of an algebra over an operad, with a view towards a conjecture formulated by the mathematician Pierre Deligne. Deligne’s (by now proven) conjecture also gives deep inights into mathematical physics. 

Die ganze Welt ist verrückt nach Kristallen

Anlässlich des internationalen Jahres der Kristallografie wurde ein Artikel aus dem Italienischen ins Deutsche für IMAGINARY übersetzt. Es geht um verschiedene Kristallstrukturen und wie man ursprünglich auf Kristallstrukturen gestoßen ist. 

Der orginal Artikel ist in der Zeitschrift XlaTangente am 1. Oktober 2014 verköffentlicht worden. Hier, geht es zum Orginal.

Katzengold: Pyrite, Plato, and a Polynomial

What are the similarities of the mineral pyrite, the dodecahedron as the fifth Platonic solid, and a polynomial of degree 16? This paper explores this connection by using the free software SURFER of the IMAGINARY open mathematics platform, which leads to fascinating pictures displaying transformations from a cube to a dodecahedron, to a rhombic dodecahedron, and to an octahedron, using a single formula. A survey on the ideas and the mathematics behind these visualizations is given.

Crystals and Mathematics

Humans have been fascinated by crystals for a long time. Its regular geometry, its special symmetry, but also its diversity in colours surprise and please us. In this article, an overview of the connection between crystals and mathematics is given. It is a contribution to the International Year of Crystallography 2014.

Zero-dimensional symmetry

This snapshot is about zero-dimensional symmetry. Thanks to recent discoveries we now understand such symmetry better than previously imagined possible. While still far from complete, a picture of zero-dimensional symmetry is beginning to emerge.

Swallowtail on the shore

Platonic solids, Felix Klein, H. S. M. Coxeter and a flap of a swallowtail: The five Platonic solids tetrahedron, cube, octahedron, icosahedron and dodecahedron have always attracted much curiosity from mathematicians, not only for their sheer beauty but also because of their many symmetry properties. In this snapshot we will start from these symmetries, move on to groups, singularities, and finally find the connection between a tetrahedron and a “swallowtail”.

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