Revisiting the free 2-generator abelian \(\ell\)-group
The free \(n\)-generator abelian \(\ell\)-group \(F_n\) was characterized by G. Birkhoff as a subdirect product of integers. \(F_n\), by a theorem due to Baer and Specker, is countable and hence \(F_n= \bigoplus_{i\in N}(\chi_i)\) for some generators \(\chi_i\). The aim of this paper is to give a description for the monoid of positive elements of \(F_n\) in the case of two generators.
scientific article; zbMATH DE number 5121393