EN
Let G be an infinite abelian p-group and let K be a field of the first kind with respect to p of characteristic different from p such that $s_p(K) = ℕ $ or $s_p(K) = ℕ ∪ 0$. The main result of the paper is the computation of the Ulm-Kaplansky functions of the factor group S(KG)/G of the normalized Sylow p-subgroup S(KG) in the group ring KG modulo G. We also characterize the basic subgroups of S(KG)/G by proving that they are isomorphic to S(KB)/B, where B is a basic subgroup of G.