MathDB
set {nx + S : n \in N}$ is finite, where nx + S ={nx + s : s \in S}

Source: Danube 2013 p4

July 22, 2019
Setsset theorycombinatorics

Problem Statement

Show that there exists a proper non-empty subset SS of the set of real numbers such that, for every real number xx, the set {nx+S:nN}\{nx + S : n \in N\} is finite, where nx+S={nx+s:sS}nx + S =\{nx + s : s \in S\}