cover all grid points by an infinite family of discs
Source: USAMO 2007
April 26, 2007
geometrycombinatoricsUSAMOcombinatorial geometrySoddy
Problem Statement
A square grid on the Euclidean plane consists of all points , where and are integers. Is it possible to cover all grid points by an infinite family of discs with non-overlapping interiors if each disc in the family has radius at least ?