Extended plus closure in complete local rings
Abstract
The (full) extended plus closure was developed as a replacement for tight closure in mixed characteristic rings. Here it is shown by adapting Andr\'{e}'s perfectoid algebra techniques that, for complete local rings that have F-finite residue fields, this closure has the colon-capturing property. In fact, more generally, if is a (possibly ramified) complete regular local ring of mixed characteristic that have F-finite residue fields, and are ideals of , and the local domain is a finite -module, then . A consequence is that all ideals in regular local rings are closed, a fact which implies the validity of the direct summand conjecture and the Brian\c{c}on-Skoda theorem in mixed characteristic.
Cite
@article{arxiv.1708.05761,
title = {Extended plus closure in complete local rings},
author = {Raymond Heitmann and Linquan Ma},
journal= {arXiv preprint arXiv:1708.05761},
year = {2018}
}
Comments
Some new applications added, and the hypothesis for the residue field to be F-finite was added to several results