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This article is cited in 2 scientific papers (total in 2 papers)
The $p$-rank of $\operatorname{Ext}_\mathbb Z(G,\mathbb Z)$ in certain models of $ZFC$
S. Shelahab, L. Strüngmanncd a Rutgers, The State University of New Jersey
b Hebrew University of Jerusalem, Department of Mathematics
c University of Hawai'i, Department of Mathematics
d University of Duisburg-Essen, Department of Mathematics
Abstract:
We prove that if the existence of a supercompact cardinal is consistent with $ZFC$, then it is consistent with $ZFC$ that the $p$-rank of $\operatorname{Ext}_\mathbb Z(G,\mathbb Z)$ is as large as possible for every prime $p$ and for any torsion-free Abelian group $G$. Moreover, given an uncountable strong limit cardinal $\mu$ of countable cofinality and a partition of $\Pi$ (the set of primes) into two disjoint subsets $\Pi_0$ and $\Pi_1$, we show that in some model which is very close to $ZFC$, there is an almost free Abelian group $G$ of size $2^\mu=\mu^+$ such that the $p$-rank of $\operatorname{Ext}_\mathbb Z(G,\mathbb Z)$ equals $2^\mu=\mu^+$ for every $p\in\Pi_0$ and 0 otherwise, that is, for $p\in\Pi_1$.
Keywords:
theory $ZFC$, supercompact cardinal, strong limit cardinal, torsion-free Abelian group, almost free Abelian group.
Received: 01.06.2006
Citation:
S. Shelah, L. Strüngmann, “The $p$-rank of $\operatorname{Ext}_\mathbb Z(G,\mathbb Z)$ in certain models of $ZFC$”, Algebra Logika, 46:3 (2007), 369–397; Algebra and Logic, 46:3 (2007), 200–215
Linking options:
https://www.mathnet.ru/eng/al302 https://www.mathnet.ru/eng/al/v46/i3/p369
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Abstract page: | 248 | Full-text PDF : | 84 | References: | 48 | First page: | 3 |
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