Meeks-Pérez-Ros conjectured in their article “Stable constant mean curvature surfaces” (2008) the following: if a closed, connected Riemannian 3-manifold N does not admit any closed, embedded minimal surfaces whose two-sided covering is stable, then N is finitely covered by the 3-sphere. Recall that a surface is called minimal if it is a critical point of … Continue reading "Stable minimal surfaces in 3-manifolds"

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 "Chromatic Number of the Plane is at least 5"