Characterizations of Warfield Groups,

Warfield groups are defined to be direct summands of simply presented abelian groups. By introducing a global definition of quasi-sequentially nice subgroups we prove some characterizations of Warfield groups involving these groups, knice subgroups, and valuated coproducts. Furthermore, we exhibit a new proof of a characterization of Warfield groups in terms of nice subgroups and valuated coproducts.