On the direct summand conjecture and its derived variant
Algebraic Geometry
2017-11-15 v2 Commutative Algebra
Abstract
Andr\'e recently gave a beautiful proof of Hochster's direct summand conjecture in commutative algebra using perfectoid spaces; his two main results are a generalization of the almost purity theorem (the perfectoid Abhyankar lemma) and a construction of certain faithfully flat extensions of perfectoid algebras where "discriminants" acquire all -power roots. In this paper, we explain a quicker proof of Hochster's conjecture that circumvents the perfectoid Abhyankar lemma; instead, we prove and use a quantitative form of Scholze's Hebbarkeitssatz (the Riemann extension theorem) for perfectoid spaces. The same idea also leads to a proof of a derived variant of the direct summand conjecture put forth by de Jong.
Keywords
Cite
@article{arxiv.1608.08882,
title = {On the direct summand conjecture and its derived variant},
author = {Bhargav Bhatt},
journal= {arXiv preprint arXiv:1608.08882},
year = {2017}
}
Comments
12 pages, comments welcome