MathDB
Coloring the points with rational coordinates

Source: Iran Third Round MO 1997, Exam 2, P3

June 30, 2012
analytic geometrynumber theoryleast common multiplecombinatorics unsolvedcombinatorics

Problem Statement

Let dd be a real number such that d2=r2+s2d^2=r^2+s^2, where rr and ss are rational numbers. Prove that we can color all points of the plane with rational coordinates with two different colors such that the points with distance dd have different colors.