Alexander Engel – Page 22

Chromatic Number of the Plane is at least 5

The problem From the usual Euclidean plane we form the following graph: the points of the plane are the vertices of our graph, and two vertices are connected by an edge if they are exactly unit distance apart. The so-called Hadwiger-Nelson problem is to compute the chromatic number of this graph, i.e., the least amount … Continue reading

Norms of infinite matrices

This is the first post of a series of posts in which we will eventually venture deep into the realm of coarse geometry. But we will always be motivated by questions which are related to the one that we will discuss here. But our first steps into coarse geometry will be very gently: we will … Continue reading

John Roe 1959-2018

John Roe, the founder of coarse index theory, passed away last month after a long fight against cancer. His web page is still online ( http://sites.psu.edu/johnroe/ ) and can be visited to get a glimpse not only of his mathematical work, but also of his personal life and all the things in the world that … Continue reading

Nemmers Prize 2018

The Frederic Esser Nemmers Prize in Mathematics goes this year to Assaf Naor “for his profound work on the geometry of metric spaces, which has led to breakthroughs in the theory of algorithms.”