A characterization of countable Butler groups
A characterization of Ext(G,ℤ) assuming (V = L)
We complete the characterization of Ext(G,ℤ) for any torsion-free abelian group G assuming Gödel’s axiom of constructibility plus there is no weakly compact cardinal. In particular, we prove in (V = L) that, for a singular cardinal ν of uncountable cofinality which is less than the first weakly compact cardinal and for every sequence of cardinals satisfying (where Π is the set of all primes), there is a torsion-free abelian group G of size ν such that equals the p-rank of Ext(G,ℤ) for every...
A consequence of a theorem of L. Fuchs
A Generalization of Baer's Splitting problem on Abelian groups.
A generalization of separable torsion-free abelian groups
A note on coflat abelian groups
A note on -adic completion of torsion-free abelian groups
A property of -groups
It is shown, under ZFC, that a -group has the interesting property of being -prebalanced in every torsion-free abelian group in which it is a pure subgroup. As a consequence, we obtain alternate proofs of some well-known theorems on -groups.
A remark on hyper-indecomposable groups
Un gruppo abeliano senza torsione ed indecomponibile è detto iperindecomponibile se tutti i sottogruppi propri del suo inviluppo iniettivo che lo contengono sono indecomponibili. In questo lavoro si caratterizza la classe dei gruppi iperindecomponibili per mezzo di loro proprietà locali. I gruppi iperindecomponibili omogenei sono caratterizzati tramite la proprietà «factor-splitting».
A result on -groups
A simple proof for a theorem of chase
Abelian group extensions and the axiom of constructibility.
Abelian groups with anti-isomorphic endomorphism rings
AE-rings
Algebraic Classes of Abelian Torsion-Free and Lattice-Ordered Groups
Algebraic ramifications of the common extension problem for group-valued measures
Let G be an Abelian group and let μ: A → G and ν: B → G be finitely additive measures (charges) defined on fields A and B of subsets of a set X. It is assumed that μ and ν agree on A ∩ B, i.e. they are consistent. The existence of common extensions of μ and ν is investigated, and conditions on A and B facilitating such extensions are given.
Algebraische Kompaktheit bei Faktorgruppen von Gruppen ganzzahliger Abbildungen.
Almost Butler groups
Generalizing the notion of the almost free group we introduce almost Butler groups. An almost -group of singular cardinality is a -group. Since almost -groups have preseparative chains, the same result in regular cardinality holds under the additional hypothesis that is a -group. Some other results characterizing -groups within the classes of almost -groups and almost -groups are obtained. A theorem of stating that a group of weakly compact cardinality having a -filtration consisting...
Almost completely decomposable groups with primary cyclic regulating quotient
Almost free splitters
Let R be a subring of the rationals. We want to investigate self splitting R-modules G, that is, such that . For simplicity we will call such modules splitters (see [10]). Also other names like stones are used (see a dictionary in Ringel’s paper [8]). Our investigation continues [5]. In [5] we answered an open problem by constructing a large class of splitters. Classical splitters are free modules and torsion-free, algebraically compact ones. In [5] we concentrated on splitters which are larger...