Minimal Diameter of Certain Sets in the Plane

We investigate the problem of finding the smallest diameterD(n) of a set ofnpoints such that all the mutual distances between them are at least 1. The asymptotic behaviour ofD(n) is known; the exact value ofD(n) can be easily found up to 6 points. Bateman and Erdős proved thatD(7)=2. In this paper we determineD(8).