Russian Combinatorics - Compass in grid
Source: 1998
March 23, 2014
rotationanalytic geometrygeometrygeometric transformationcombinatorics unsolvedcombinatorics
Problem Statement
The endpoints of a compass are at two lattice points of an infinite unit square
grid. It is allowed to rotate the compass around one of its endpoints, not varying
its radius, and thus move the other endpoint to another lattice point. Can the
endpoints of the compass change places after several such steps?