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Mathematische Annalen
Article . 1995 . Peer-reviewed
License: Springer TDM
Data sources: Crossref
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
zbMATH Open
Article . 1995
Data sources: zbMATH Open
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Abelian localp-class field theory

Abelian local \(p\)-class field theory
Authors: Fesenko, Ivan B.;

Abelian localp-class field theory

Abstract

In the first section an abstract \(p\)-class field theory is developed. Assume that the ground field \(K\) possesses a distinguished Galois extension \(\widetilde {K}/K\) with the Galois group being an abelian pro- \(p\)-group. Then for a finite separable extension \(F/K\) Galois \(p\)- extensions \(L/F\) linearly disjoint with \(\widetilde {F}/F\), \(\widetilde {F}= F\widetilde {K}\) (these extensions are said to be totally ramified) are described by means of a suitable modulation \({\mathcal A}= \{A_ F\): \(F/K\}\). One can introduce a map \(\Upsilon_{L/F}\) acting from the group \(\text{Gal} (L/F)^ \sim\), of continuous \(\mathbb{Z}_ p\)-homomorphisms from \(\text{Gal} (\widetilde {F}/ F)\) to the discrete group \(\text{Gal} (L/F)\), to the quotient group \(U_ F/ N_{L/F} U_ L\), where \(U_ F\) is the kernel of the substantial epimorphism \(v: A_ F\to \mathbb{Z}\). This map is a generalization of the Neukirch map in the classical cases. One of the main conditions on which the theory rests is Hilbert Satz 90 for \(A_ F\). At the same time several other reasonable properties, such as \(\text{Gal} (L/F)\)-stable elements of \(A_ L\) are in one-to-one correspondence with elements of \(A_ F\), are not assumed to hold in general. Thereby, first of all we consider extensions for which a weaker condition: \[ v_{\widetilde {L}} (A_{\widetilde {L}}^{\text{Gal} (\widetilde {L}/\widetilde {F})})= | \widetilde{L} : \widetilde{F}\mid \mathbb{Z} \] holds for a cyclic \(p\)-extension \(\widetilde {L}/ \widetilde {F}\). The class of such extensions (they are called marked) is required to be sufficiently large. For a totally ramified Galois extension \(L/F\), such that any of its intermediate cyclic subextensions \(L_ 1/ F_ 1\) \((F\subset F_ 1\subset L_ 1\subset L)\) is marked, one can define a homomorphism \(\Psi_{L/F}\) (as a generalization of the Hazewinkel homomorphism in one-dimensional case) acting from \(U_ F/ N_{L/F} U_ L\) to \((\text{Gal} (L/F)^{\text{ab}} )^ \sim\); the composition \(\Psi_{L/F} \circ \Upsilon_{L/F}\) is the identity map. Then, assumption on the surjectivity of \(\Upsilon_{L/F}\) for a marked extension of degree \(p\) permits one to show that \(\Upsilon_{L/F}\) and \(\Psi_{L/F}\) are inverse isomorphisms between \((\text{Gal} (L/F)^{\text{ab}} )^ \sim\) and \(U_ F/ N_{L/F} U_ L\). The general case of totally ramified Galois extensions can be handled as well: the definition of \(\Psi_{L/F}\) isn't extendable to arbitrary extensions, but \(\Upsilon_{L/F}\) remains an isomorphism. The next sections contain \(p\)-class field theory for a complete discrete valuation field \(F\) of rank \(n\) with non-algebraically-\(p\)-closed residue field \(k\). Abelian totally ramified (with respect to the discrete valuation of rank \(n\)) \(p\)-extensions are described by means of the subgroup \(VK_ n^{\text{top}} (F)\) in the Milnor topological \(K\)- group \(K_ n^{\text{top}} (F)\), generated by principal units with respect to the discrete valuation. Here for \(n\geq 2\) so-called \(\wp\)- extensions (a tower of subsequent Artin-Schreier extensions) as marked extensions are chosen. The reciprocity map is established: \[ \Psi_ F :VK_ n^{\text{top}} (F)\to \Hom_{\mathbb{Z}_ p} (\text{Gal} (\widetilde {F}/ F), \text{Gal} (F_ p^{\text{ab}}/ \widetilde {F})), \] where \(\widetilde {F}/ F\) is the maximal unramified, with respect to the discrete valuation of rank \(n\), subextension in \(F_ p^{\text{ab}}/ F\), \(F_ p^{\text{ab}}\) is the maximal abelian \(p\)- extension of \(F\). This approach gives, in particular, a new elementary proof of the \(p\)-part of class field theory in the case of higher dimensional local fields with finite residue field. The next sections of the paper contain applications to ramification theory in the case of imperfect residue field (a definition of the Hasse- Herbrand function is exposed); and an existence theorem: description of norm subgroups in \(VK_ n^{\text{top}} (F)\) via the theory of decomposable additive polynomials.

Country
Germany
Keywords

\(K\)-theory of local fields, elementary proof of \(p\)-part of class field theory, Class field theory; \(p\)-adic formal groups, abelian totally ramified \(p\)-extensions, Milnor topological \(K\)-group, ramification, Hilbert Satz 90, Hasse-Herbrand function, Class field theory, Galois \(p\)-extensions, Article, generalization of the Neukirch map, Ramification and extension theory, generalization of the Hazewinkel homomorphism, 510.mathematics, Artin-Schreier extensions, abstract \(p\)-class field theory, imperfect residue field, Generalized class field theory (\(K\)-theoretic aspects), Higher symbols, Milnor \(K\)-theory, higher dimensional local fields, norm subgroups, complete discrete valuation field

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
17
Average
Top 10%
Average
Green