MathDB
Reals modulo 1 arise

Source: RMM Extralist 2021 A3

September 18, 2023
RMM Shortlistalgebraintervalscoveringcombinatorics

Problem Statement

A tile TT is a union of finitely many pairwise disjoint arcs of a unit circle KK. The size of TT, denoted by T|T|, is the sum of the lengths of the arcs TT consists of, divided by 2π2\pi. A copy of TT is a tile TT' obtained by rotating TT about the centre of KK through some angle. Given a positive real number ε<1\varepsilon < 1, does there exist an infinite sequence of tiles T1,T2,,Tn,T_1,T_2,\ldots,T_n,\ldots satisfying the following two conditions simultaneously: 1) Tn>1ε|T_n| > 1 - \varepsilon for all nn; 2) The union of all TnT_n' (as nn runs through the positive integers) is a proper subset of KK for any choice of the copies T1T_1', T2T_2', \ldots, Tn,T_n', \ldots?
In the extralist the problem statement had the clause "three conditions" rather than two, but only two are presented, the ones you see. I am quite confident this is a typo or that the problem might have been reformulated after submission.