In this paper, using the notion of the tight integral closure, we will give a criterion for F-rationality of Rees algebras of α-primary ideals in a Ε½ . CohenαMacaulay local ring. As its application, we prove the following results: 1 In dimension two, if A is F-rational and I is integrally closed, th
Rees Algebras of F-regular Type
β Scribed by Nobuo Hara; Kei-ichi Watanabe; Ken-ichi Yoshida
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 195 KB
- Volume
- 247
- Category
- Article
- ISSN
- 0021-8693
No coin nor oath required. For personal study only.
β¦ Synopsis
We study the F-regularity of Rees algebras R I s A It in terms of the global Ε½ . F-regularity of the blowing-up X s Proj R I of Spec A. As it reads, global F-regularity is a global analog of strong F-regularity defined via splitting of Frobenius maps in prime characteristic, and these notions are extended to charac-Ε½ . teristic zero by reduction modulo p 4 0. We study in detail the case where A, α is a two-dimensional local ring and I is an α-primary ideal. In characteristic zero, Ε½ . the condition for R I to have F-regular type is described in terms of the dual graph of a resolution X on which IO O is invertible. We also prove some X miscellaneous results concerning singularities of Rees algebras and extended Rees algebras of higher dimension.
π SIMILAR VOLUMES
In a previous paper we exhibited the somewhat surprising property that most direct links of prime ideals in Gorenstein rings are equimultiple ideals with reduction number 1. This led to the construction of large families of Cohen-Macaulay Rees algebras. The first goal of this paper is to extend this