Polynomially-Rich Lines or Circles in Sets with Few Triangles

Jonathan Passant, University of Bristol

Date and time: 2pm (New York time), Tuesday, November 22, 2022

Place: On Zoom (details provided on the seminar mailing list)

A harder version of Erdős’ famous distinct-distances problem asks about the structure of point sets in the plane that have few distances. In particular, Erdős asked if such near-optimal sets have a ‘lattice structure’ or, given this appears very hard, if a polynomial proportion of the points lie on a line. We consider sets with few congruent triangles, showing such sets contain either a polynomially-rich line or a positive proportion of the set on a circle. There will also be some discussion of energy results in such a setting. Our methods use a Balog-Szemerédi-Gowers type result over the Euclidian group along with classical results from additive combinatorics.