Archimedean Unital Groups with Finite Unit Intervals

Let G be a unital group with a finite unit interval E, let n be the number of atoms in E, and let κ be the number of extreme points of the state spaceΩ(G). We introduce canonical order-preserving group homomorphisms ξ : Zn → G and ρ : G → Zκ linking G with the simplicial groups Zn and Zκ . We show that ξ is a surjection and ρ is an injection if and only if G is torsion-free. We give an explicit construction of the universal group (unigroup) for E using the canonical surjection ξ. If G is torsion-free, then the canonical injection ρ is used to show that G is Archimedean if and only if its positive cone is determined by a finite number of homogeneous linear inequalities with integer coefficients.