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Journal of Algebraic Geometry

Journal of Algebraic Geometry

Online ISSN 1534-7486; Print ISSN 1056-3911

   
 
 

 

An analogue of adjoint ideals and PLT singularities in mixed characteristic


Authors: Linquan Ma, Karl Schwede, Kevin Tucker, Joe Waldron and Jakub Witaszek
Journal: J. Algebraic Geom. 31 (2022), 497-559
DOI: https://doi.org/10.1090/jag/797
Published electronically: May 5, 2022
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Abstract | References | Additional Information

Abstract: We use the framework of perfectoid big Cohen-Macaulay (BCM) algebras to define a class of singularities for pairs in mixed characteristic, which we call purely BCM-regular singularities, and a corresponding adjoint ideal. We prove that these satisfy adjunction and inversion of adjunction with respect to the notion of BCM-regularity and the BCM test ideal defined by the first two authors. We compare them with the existing equal characteristic purely log terminal (PLT) and purely $F$-regular singularities and adjoint ideals. As an application, we obtain a uniform version of the Briançon-Skoda theorem in mixed characteristic. We also use our theory to prove that two-dimensional Kawamata log terminal singularities are BCM-regular if the residue characteristic $p>5$, which implies an inversion of adjunction for three-dimensional PLT pairs of residue characteristic $p>5$. In particular, divisorial centers of PLT pairs in dimension three are normal when $p > 5$. Furthermore, in Appendix A we provide a streamlined construction of perfectoid big Cohen-Macaulay algebras and show new functoriality properties for them using the perfectoidization functor of Bhatt and Scholze.


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Linquan Ma
Affiliation: Department of Mathematics, Purdue University, West Lafayette, Indiana 47907
MR Author ID: 1050700
Email: ma326@purdue.edu

Karl Schwede
Affiliation: Department of Mathematics, University of Utah, Salt Lake City, Utah 84112
MR Author ID: 773868
Email: schwede@math.utah.edu

Kevin Tucker
Affiliation: Department of Mathematics, University of Illinois at Chicago, Chicago, Illinois 60607
MR Author ID: 888804
ORCID: 0000-0003-1255-2665
Email: kftucker@uic.edu

Joe Waldron
Affiliation: Department of Mathematics, Princeton University, Princeton, New Jersey 08544
MR Author ID: 1213375
Email: jaw8@princeton.edu

Jakub Witaszek
Affiliation: Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109
MR Author ID: 1110594
ORCID: 0000-0002-3728-4305
Email: jakubw@umich.edu

Received by editor(s): June 25, 2020
Published electronically: May 5, 2022
Additional Notes: The first author was supported by NSF Grant DMS #1901672, NSF FRG Grant #1952366, and a fellowship from the Sloan Foundation. The second author was supported by NSF CAREER Grant DMS #1252860/1501102, NSF FRG Grant #1952522, and NSF Grants #1801849 and #2101800. The third author was supported by NSF Grants DMS #1602070 and #1707661, and by a fellowship from the Sloan Foundation. The fourth author was supported by the Simons Foundation under Grant No. 850684. The fifth author was supported by the National Science Foundation under Grant No. DMS-1638352 at the Institute for Advanced Study in Princeton as well as by NSF Grant DMS-2101897. This material was partially based upon work supported by the National Science Foundation under Grant No. DMS-1440140 while the authors were in residence at the Mathematical Sciences Research Institute in Berkeley, California, during the Spring 2019 semester. The authors also worked on this while attending an AIM SQUARE in June 2019.
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