English

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

Commutative Algebra 2016-04-11 v1

Abstract

Let (R,m)(R, \mathfrak m) be a commutative noetherian local ring. We investigate under which conditions an RR-module MM is generated by an ideal II, i.e. there exists an epimorphism I(Λ)MI^{(\Lambda)} \twoheadrightarrow M. If MM is uniserial, i.e. L(M)\mathcal{L}(M) is totally ordered and finite, this is equivalent to mn1I⊄AnnR(M)I\mathfrak{m}^{n-1} \cdot I \not\subset \operatorname{Ann}_R(M) \cdot I (length(M)=n1\operatorname{length}(M) = n \geq 1). If MM is cyclic and I=mI = \mathfrak{m}, this is equivalent to: Either it is MR/pM \cong R/\mathfrak{p} (R/pR/\mathfrak{p} a discrete valuation ring) or MC/So(C)M \cong C/\operatorname{So}(C) (CC a uniserial RR-module). If AA is free and BB is a submodule of AA, then the Matlis dual (A/B)=operatornameHomR(A/B,E)(A/B)^{\circ} = operatorname{Hom}_R(A/B, E) is II-generated if and only if B=(IB):AIB = (IB) :_A I. In the case I=mI = \mathfrak{m}, this condition leads to the "basically full ideals" considered by Heinzer, Ratliff~Jr. and Rush. By studying the dual condition M=I(M:XI)M = I(M :_X I) in the last section, we can generalize some results of that work.

Keywords

Cite

@article{arxiv.1604.02349,
  title  = {\"Uber die von einem Ideal $I \subset R$ erzeugten $R$-Moduln},
  author = {Helmut Zöschinger},
  journal= {arXiv preprint arXiv:1604.02349},
  year   = {2016}
}

Comments

9 pages, in German