Small Positive Values of Indefinite Quadratic Forms
J. H. H. Chalk · Canadian Mathematical Bulletin · 1963
Let ∧ denote the lattice of points X = (x1, …, xn) with integral coordinates. A basis of ∧ is a set of n points X1, …, Xn of ∧ such that every point of ∧ is expressible in the form where ui are integers. It is easy to see that points X1, …, Xn of ∧ form a basis if, and only if (1) where Xr = (x1(r), …, x1(r)).