English

The Ohm-Rush content function III: Completion, globalization, and power-content algebras

Commutative Algebra 2021-03-01 v3

Abstract

One says that a ring homomorphism RSR \rightarrow S is Ohm-Rush if extension commutes with arbitrary intersection of ideals, or equivalently if for any element fSf\in S, there is a unique smallest ideal of RR whose extension to SS contains ff, called the content of ff. For Noetherian local rings, we analyze whether the completion map is Ohm-Rush. We show that the answer is typically `yes' in dimension one, but `no' in higher dimension, and in any case it coincides with the content map having good algebraic properties. We then analyze the question of when the Ohm-Rush property globalizes in faithfully flat modules and algebras over a 1-dimensional Noetherian domain, culminating both in a positive result and a counterexample. Finally, we introduce a notion that we show is strictly between the Ohm-Rush property and the weak content algebra property.

Keywords

Cite

@article{arxiv.2008.07616,
  title  = {The Ohm-Rush content function III: Completion, globalization, and power-content algebras},
  author = {Neil Epstein and Jay Shapiro},
  journal= {arXiv preprint arXiv:2008.07616},
  year   = {2021}
}

Comments

Little changes made throughout. 14 pages. Comments welcome!

R2 v1 2026-06-23T17:55:18.946Z