English

\"Uber die von einem Ideal $I \subset R$ erzeugten $R$-Moduln II

Commutative Algebra 2017-05-10 v1 Rings and Algebras

Abstract

Let (R,m)(R, \mathfrak m) be a commutative noetherian local ring and II an ideal of RR. Let P\mathcal{P} be the class of all II-generated RR-modules MM (i.e. there is an epimorphism I(Λ)MI^{(\Lambda)} \twoheadrightarrow M) and let S\mathcal{S} be the class of all II^{\circ}-cogenerated RR-modules NN (i.e. there is a monomorphism N(I)ΛN \hookrightarrow (I^{\circ})^{\Lambda} with I=HomR(I,E)I^{\circ} = \operatorname{Hom}_R(I,E)). We give a complete description of all injective and flat modules in P\mathcal{P} and S\mathcal{S}. We show that (S,P)(\mathcal{S},\mathcal{P}) forms a dual pair in the sense of Mehdi--Prest(2015) and that P\mathcal{P} is always closed under pure submodules. We determine all ideals II for which P\mathcal{P} is closed under submodules, S\mathcal{S} is closed under factor modules and P\mathcal{P} (resp. S\mathcal{S}) is closed under group extensions. In the last section, we examine the submodules γ(M)={UMUP}\gamma(M) = \sum\{U \subset M \,|\, U \in \mathcal{P}\} and κ(M)={VMM/VS}\kappa(M) = \bigcap \{V \subset M \,|\, M/V \in \mathcal{S}\} for all RR-modules MM, and we specify their explicit structure in special cases.

Keywords

Cite

@article{arxiv.1705.03353,
  title  = {\"Uber die von einem Ideal $I \subset R$ erzeugten $R$-Moduln II},
  author = {Helmut Zöschinger},
  journal= {arXiv preprint arXiv:1705.03353},
  year   = {2017}
}

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