منابع مشابه
Pure extensions of locally compact abelian groups
In this paper, we study the group Pext(C, A) for locally compact abelian (LCA) groups A and C. Sufficient conditions are established for Pext(C, A) to coincide with the first Ulm subgroup of Ext(C, A). Some structural information on pure injectives in the category of LCA groups is obtained. Letting C denote the class of LCA groups which can be written as the topological direct sum of a compactl...
متن کاملPure-injective modules
The pure-injective R-modules are defined easily enough: as those modules which are injective over all pure embeddings, where an embedding A → B is said to be pure if every finite system of R-linear equations with constants from A and a solution in B has a solution in A. But the definition itself gives no indication of the rich theory around purity and pure-injectivity. The purpose of this surve...
متن کاملSuperdecomposable pure-injective modules
Existence of superdecomposable pure-injective modules reflects complexity in the category of finite-dimensional representations. We describe the relation in terms of pointed modules. We present methods for producing superdecomposable pure-injectives and give some details of recent work of Harland doing this in the context of tubular algebras. 2010 Mathematics Subject Classification. Primary 16G...
متن کاملOn Extensions of Primary Almost Totally Projective Abelian Groups
Suppose G is a subgroup of the reduced abelian p-group A. The following two dual results are proved: (∗) If A/G is countable and G is an almost totally projective group, then A is an almost totally projective group. (∗∗) If G is countable and nice in A such that A/G is an almost totally projective group, then A is an almost totally projective group. These results somewhat strengthen theorems du...
متن کاملG.C.H. implies existence of many rigid almost free abelian groups
This result has been generalized in various directions, e.g. replacing the ground ring Z by a more general ring and dropping the cardinal restriction (in Corner’s result this is actually |A| < 20), see [2], [20], [8], [9], [4], [23]. Other extensions include abelian groups which are not necessarily torsionfree, see Corner, Göbel [4] for references. Here we are interested in a different strength...
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ژورنال
عنوان ژورنال: Rocky Mountain Journal of Mathematics
سال: 1979
ISSN: 0035-7596
DOI: 10.1216/rmj-1979-9-3-569