English

A Generalized Contou-Carr\`ere Symbol and its Reciprocity Laws in Higher Dimensions

Algebraic Geometry 2021-05-12 v4 K-Theory and Homology Number Theory Representation Theory

Abstract

We generalize the theory of Contou-Carr\`ere symbols to higher dimensions. To an (n+1)(n+1)-tuple f0,,fnA((t1))((tn))×f_0,\dots,f_n \in A((t_1))\cdots((t_n))^{\times}, where AA denotes a commutative algebra over a field kk, we associate an element (f0,,fn)A×(f_0,\dots,f_n) \in A^{\times}, compatible with the higher tame symbol for k=Ak = A, and earlier constructions for n=1n = 1, by Contou-Carr\`ere, and n=2n = 2 by Osipov--Zhu. Our definition is based on the notion of \emph{higher commutators} for central extensions of groups by spectra, thereby extending the approach of Arbarello--de Concini--Kac and Anderson--Pablos Romo. Following Beilinson--Bloch--Esnault for the case n=1n=1, we allow AA to be arbitrary, and do not restrict to artinian AA. Previous work of the authors on Tate objects in exact categories, and the index map in algebraic KK-theory is essential in anchoring our approach to its predecessors. We also revisit categorical formal completions, in the context of stable \infty-categories. Using these tools, we describe the higher Contou-Carr\`ere symbol as a composition of boundary maps in algebraic KK-theory, and conclude the article by proving a version of Parshin--Kato reciprocity for higher Contou-Carr\`ere symbols.

Keywords

Cite

@article{arxiv.1410.3451,
  title  = {A Generalized Contou-Carr\`ere Symbol and its Reciprocity Laws in Higher Dimensions},
  author = {Oliver Braunling and Michael Groechenig and Jesse Wolfson},
  journal= {arXiv preprint arXiv:1410.3451},
  year   = {2021}
}

Comments

62 pages, introduction completely rewritten, final pre-publication version