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The Kadison-Singer problem

In quantum mechanics, unlike in classical mechanics, one cannot make precise predictions about how a system will behave. Instead, one is concerned with mere probabilities. Consequently, it is a very important task to determine the basic probabilities associated with a given system. In this snapshot we will present a recent uniqueness result concerning these probabilities.

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”.

Statistics and dynamical phenomena

A friend of mine, an expert in statistical genomics, told me the following story: At a dinner party, an attractive lady asked him, “What do you do for a living?” He replied, “I model.” As my friend is a handsome man, the lady did not question his statement and continued, “What do you model?” “Genes.” She then looked at him up and down and said, “Mh, you must be very much in demand.” “Yes, very much so, especially after I helped discover a new culprit gene for a common childhood disease.” The lady looked puzzled.

Minimizing energy

What is the most efficient way to fence land when you’ve only got so many metres of fence? Or, to put it differently, what is the largest area bounded by a simple closed planar curve of fixed length?
We consider the answer to this question and others like it, making note of recent results in the same spirit.

The epita-dodecahedron visualizing Poincaré's dodecahedral space

Analogous to Henri Poincaré’s concept of dodecahedral space the epita_dodecahedron allows to visualize the principle of the counter-movements of the opposite polyhedra E+ instead of the pentagonal spaces in his description of the homology sphere in the fifth “Complément” : Thus it clearly shows the different evolving symmetries,- crystallizing in steps of 36 degrees, just as Poincaré anticipated the shape of the universe in 1904.

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