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 ex
F-Rationality of Rees Algebras
β Scribed by Nobuo Hara; Kei-ichi Watanabe; Ken-ichi Yoshida
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 262 KB
- Volume
- 247
- Category
- Article
- ISSN
- 0021-8693
No coin nor oath required. For personal study only.
β¦ Synopsis
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, then the Rees Ε½ . algebra R I is F-rational. On the other hand, in higher dimensions, we construct many examples of CohenαMacaulay, normal Rees algebras which are not F-Ε½ . Ε½ . rational. 2 If both A and R I are F-rational, then so is the extended Rees
On the other hand, using resolution of singularities, we will prove that a two-dimensional rational singularity always admits F-rational Rees algebras. In Ε½ particular, this theorem gives another way than that devised by Watanabe 1997, J.
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