Four points in the plane with pairwise odd integral distances do not exist. The maximum number of odd distances between n points in the plane is proved to be n(2)/3+r r(r-3)/6 for all n, where r=1,2,3 and n=r (mod 3). This solves a recently stated problem of Erdos.
机构:
Univ Cambridge, Dept Pure Math & Math Stat, Wilberforce Rd, Cambridge CB3 0WB, EnglandUniv Cambridge, Dept Pure Math & Math Stat, Wilberforce Rd, Cambridge CB3 0WB, England