MathDB
polyline of length 200 in a square of side 1 (2019 Novosibirsk Oral Geo Oly 9.6)

Source:

April 28, 2021
geometrypolyline

Problem Statement

A square with side 11 contains a non-self-intersecting polyline of length at least 200200. Prove that there is a straight line parallel to the side of the square that has at least 101101 points in common with this polyline.