3 citations · 4 across the 9 of their papers we have counts for
9 papers
Cellular covers of cotorsion-free modules
Rüdiger Göbel, José L. Rodríguez, Lutz Strüngmann
In this paper we improve recent results dealing with cellular covers of -modules. Cellular covers (sometimes called co-localizations) come up in the context of homotopical local…
Filtration equivalent aleph_1-separable abelian groups of cardinality aleph_1
Saharon Shelah, Lutz Strüngmann
We show that it is consistent with ordinary set theory ZFC and the generalized continuum hypothesis that there exist two separable abelian groups of cardinality aleph_1 which are f…
A characterization of Ext(G,Z) assuming V=L
Saharon Shelah, Lutz Strüngmann
In this paper we complete the characterization of Ext(G,Z) under Godel's axiom of constructibility for any torsion-free abelian group G . In particular, we prove in (V=L) that, for…
On the p-rank of Ext_Z(G,Z) in certain models of ZFC
Saharon Shelah, Lutz Strüngmann
We show that if the existence of a supercompact cardinal is consistent with ZFC, then it is consistent with ZFC that the p-rank of Ext_Z(G, Z) is as large as possible for every pri…
Generalized E-Rings
Rüdiger Göbel, Saharon Shelah, Lutz Strüngmann
A ring R is called an E-ring if the canonical homomorphism from R to the endomorphism ring End(R_Z) of the additive group R_Z, taking any r in R to the endomorphism left multiplica…
Almost-free E-rings of cardinality aleph_1
Rüdiger Göbel, Saharon Shelah, Lutz Strüngmann
An E-ring is a unital ring R such that every endomorphism of the underlying abelian group R^+ is multiplication by some ring-element. The existence of almost-free E-rings of cardin…