| heal.abstract |
Let x1, . . . , xn be linearly independent positive functions in C(Ω), let X be the vector subspace generated by the xi and let β denote the curve of ℝn determined by the function β(t) = 1/z(t)(x1(t),x2(t), . . . , xn(t)), where z(t) = x1(t) +x2(t) + ⋯ + xn(t). We establish that X is a vector lattice under the induced ordering from C(Ω) if and only if there exists a convex polygon of ℝn with n vertices containing the curve β and having its vertices in the closure of the range of β. We also present an algorithm which determines whether or not X is a vector lattice and in case X is a vector lattice it constructs a positive basis of X. The results are also shown to be valid for general normed vector lattices. © 1996 American Mathematical Society. |
en |