Marco Golla (U. Nantes), The square peg problem and surfaces in 4-manifolds

The square peg problem asks whether every Jordan curve in the plane contains the vertices of a square. Inspired by Hugelmeyer's approach for smooth curves, we give a topological proof for (locally) 1-Lipschitz functions using Möbius bands and elementary 4-dimensional topology. This is joint work with Peter Feller.