Flat commutative ring epimorphisms of almost Krull dimension zero

Abstract

We consider flat epimorphisms of commutative rings $R\to U$ such that, for every ideal $I\subset R$ for which $IU=U$, the quotient ring $R/I$ is semilocal of Krull dimension zero. Under these assumptions, we show that the projective dimension of the $R$-module $U$ does not exceed $1$. We also describe the Geigle-Lenzing perpendicular subcategory $U^{{\perp }_{0,1}}$ in $R-\mathsf{Mod}$. Assuming additionally that the ring $U$ and all the rings $R/I$ are perfect, we show that all flat $R$-modules are $U$-strongly flat. Thus we obtain a generalization of some results of the paper arXiv:1801.04820, where the case of the localization $U=S^{-1}R$ of the ring $R$ at a multiplicative subset $S\subset R$ was considered.

LaTeX 2e, 17 pages; v.2: small expositional improvements, references updated; v.3: two misprints corrected -- this is intended as the final version

References in corpus (1)

• Remarks on derived complete modules and complexes