Problem: How many colors are needed so that if each point in the plane is assigned one of the colors, no two points which are exactly distance 1 apart will be assigned the same color? This problem has ...

Aubrey de Grey present a family of finite unit-distance graphs in the plane that are not 4-colorable, thereby improving the lower bound of the HadwigerNelson problem. The smallest such graph that we ...

This is a preview. Log in through your library . Journal Information The Mathematical Gazette is the original journal of the Mathematical Association and it is now over a century old. Its readership ...