Date and time: Monday, Nov 30, 2020, 4:30pm (online)

Por: Sergei Tabachnikov, Penn State Univ, USA

Title: Elementary geometry is dead. Long live (experimental) elementary geometry!

Abstract: By "elementary" I do not mean Euclidean, axiomatic, high school geometry, nor do I mean that these results are expected or easy to obtain: I use this term to distinguish this subject from differential geometry. I have a collection of recent results that fall into this category, and I shall present a sampler; in most cases, these results were discovered in computer experiments and were motivated by the theory of completely integrable systems. The topics will include the circumcenter of mass of polygons, a new take on Steiner's porism, new projective configuration theorems, and lesser known geometrical properties of Poncelet polygons.