Fiber cones and the integral closure of ideals
نویسنده
چکیده
Let (R,m) be a Noetherian local ring and let I ⊆ R be an ideal. This paper studies the question of when mI is integrally closed. Particular attention is focused on the case R is a regular local ring and I is a reduced ideal. This question arose through a question posed by Eisenbud and Mazur on the existence of evolutions. Let (R,m) be a Noetherian local ring and let I ⊆ R be an ideal. In this paper we are interested in the question of when mI is integrally closed. To explain our motivation for studying this question, we recall the definition of an evolution [5]. Definition 1.1. Let k be a ring and let T be a local k-algebra essentially of finite type over k. An evolution of T over k is a local k-algebra R, essentially of finite type, and a surjection R → T of k-algebras inducing an isomorphism ΩR/k ⊗R T ∼= ΩT/k. The evolution is trivial if R → T is an isomorphism, and T is evolutionarily stable over k if all evolutions are trivial. It is possible that over a field k of characteristic 0, every reduced local k-algebra T essentially of finite type over k is evolutionarily stable. No counterexamples are known. See [5, 7, 13] for some partial results. The question concerning the existence
منابع مشابه
Fiber Cones of Ideals with Almost Minimal Multiplicity
Fiber cones of 0-dimensional ideals with almost minimal multiplicity in CohenMacaulay local rings are studied. Ratliff-Rush closure of filtration of ideals with respect to another ideal is introduced. This is used to find a bound on the reduction number with respect to an ideal. Rossi’s bound on reduction number in terms of Hilbert coefficients is obtained as a consequence. Sufficient condition...
متن کاملTopics on the Ratliff-Rush Closure of an Ideal
Introduction Let be a Noetherian ring with unity and be a regular ideal of , that is, contains a nonzerodivisor. Let . Then . The :union: of this family, , is an interesting ideal first studied by Ratliff and Rush in [15]. The Ratliff-Rush closure of is defined by . A regular ideal for which is called Ratliff-Rush ideal. The present paper, reviews some of the known prop...
متن کاملON FIBER CONES OF m-PRIMARY IDEALS
Two formulas for the multiplicity of the fiber cone F (I) = ⊕∞n=0I /mI of an m-primary ideal of a d-dimensional Cohen-Macaulay local ring (R,m) are derived in terms of the mixed multiplicity ed−1(m|I), the multiplicity e(I) and superficial elements. As a consequence, the Cohen-Macaulay property of F (I) when I has minimal mixed multiplicity or almost minimal mixed multiplicity is characterized ...
متن کاملMixed Segre Numbers and Integral Closure of Ideals
We introduce mixed Segre numbers of ideals which generalize the notion of mixed multiplicities of ideals of finite colength and show how many results on mixed multiplicities can be extended to results on mixed Segre numbers. In particular, we give a necessary and sufficient condition in terms of these numbers for two ideals to have the same integral closure. Also, our theory yields a new proof ...
متن کاملTight Closure and plus Closure for Cones over Elliptic Curves
We characterize the tight closure of graded primary ideals in a homogeneous coordinate ring over an elliptic curve by numerical conditions and we show that it is in positive characteristic the same as the plus closure.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2000