Hostname: page-component-848d4c4894-4hhp2 Total loading time: 0 Render date: 2024-05-13T07:04:34.332Z Has data issue: false hasContentIssue false

A Relative Filtration Index and Fibers of Normal Primes in Extensions of Finite Type

Published online by Cambridge University Press:  04 December 2007

PHILLIP GRIFFITH
Affiliation:
Department of Mathematics, University of Illinois, 1409 West Green Street, Urbana, Illinois 61801, USA; e-mail: griffith@math.uiuc.edu
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

For an extension R [rarrhk ] A of commutative Noetherian rings the behavior of the associated morphism of topological spaces Spec A → Spec R is often measured by its behavior on each of its fibers. Specifically, one studies the ’splitting‘ (or ’branching‘) and the ’ramification‘ that occurs in each fiber. In the classical constructions of faithfully flat analytic extensions (e.g., completion or Henselization) of excellent local rings the splitting and ramification properties are fairly well understood; see EGA IV [6, 18.10], Nagata [13, Sect. 37] or Raynaud [15, Ch. IX]. The strongest results are usually achieved for fibers over a ’normal point‘ of Spec R, that is, over p ∈ Spec R such that R/p is a normal domain [e.g., the property of a normal prime p in a local ring to be ’unibranched‘, i.e., the Henselization of R/p is a (normal) domain].

Type
Research Article
Copyright
© 1998 Kluwer Academic Publishers