Integral closure of ideals, rings, and modules by Irena Swanson, Craig Huneke

By Irena Swanson, Craig Huneke

Quintessential closure has performed a job in quantity idea and algebraic geometry because the 19th century, yet a contemporary formula of the idea that for beliefs probably begun with the paintings of Krull and Zariski within the Nineteen Thirties. It has constructed right into a device for the research of many algebraic and geometric difficulties. This ebook collects jointly the significant notions of fundamental closure and offers a unified remedy. innovations and subject matters lined contain: habit of the Noetherian estate lower than indispensable closure, analytically unramified earrings, the conductor, box separability, valuations, Rees algebras, Rees valuations, savings, multiplicity, combined multiplicity, joint mark downs, the Briançon-Skoda theorem, Zariski's concept of integrally closed beliefs in two-dimensional typical neighborhood jewelry, computational features, adjoints of beliefs and common homomorphisms. With many labored examples and routines, this e-book will offer graduate scholars and researchers in commutative algebra or ring thought with an approachable advent top into the present literature.

Show description

Read or Download Integral closure of ideals, rings, and modules PDF

Similar algebra & trigonometry books

An Algebraic Introduction to Complex Projective Geometry: Commutative Algebra

During this creation to commutative algebra, the writer choses a course that leads the reader throughout the crucial principles, with out getting embroiled in technicalities. he is taking the reader quick to the basics of complicated projective geometry, requiring just a easy wisdom of linear and multilinear algebra and a few straight forward crew concept.

Inequalities : a Mathematical Olympiad approach

This publication is meant for the Mathematical Olympiad scholars who desire to organize for the research of inequalities, a subject now of widespread use at a number of degrees of mathematical competitions. during this quantity we current either vintage inequalities and the extra valuable inequalities for confronting and fixing optimization difficulties.

Recent Progress in Algebra: An International Conference on Recent Progress in Algebra, August 11-15, 1997, Kaist, Taejon, South Korea

This quantity offers the complaints of the overseas convention on ""Recent development in Algebra"" that was once held on the Korea complex Institute of technology and expertise (KAIST) and Korea Institute for complicated examine (KIAS). It introduced jointly specialists within the box to debate development in algebra, combinatorics, algebraic geometry and quantity concept.

Additional info for Integral closure of ideals, rings, and modules

Sample text

9 Let R ⊆ S be an inclusion of rings, and let x1 , . . , xn ∈ S. The following are equivalent: (1) For all 1 ≤ i ≤ n, xi is integral over R. (2) R[x1 , . . , xn ] is a finitely generated R-submodule of S. (3) There is a non-zero finitely generated R-module M ⊆ S such that xi M ⊆ M for each 1 ≤ i ≤ n and such that M is a faithful R[x1 , . . , xn ]-module. Proof: Assume (1). We use induction on n to prove (2). By induction we may assume that R[x1 , . . , xn−1 ] is a finitely generated R-submodule of S.

Tc , t−1 1 , . . , tc ]. This proves that −1 T = T0 [t1 , . . , tc , t−1 1 , . . , tc ], with t1 , . . , tc variables over the field T0 . In particular, T is (a localization) of a unique factorization domain, hence T is integrally closed. This proves (1). 6 Let R be a reduced N-graded ring, possibly non-Noetherian, such that the non-zero elements of R0 are non-zerodivisors in R. Then the integral closure of R is N-graded. Proof: Let α ∈ R. By writing α as a quotient of two elements of R and by collecting all the homogeneous parts of the two elements and of the coefficients of an equation of integral dependence, we see that there exist finitely many homogeneous elements x1 , .

In other words, the nilpotent elements behave trivially under the integral closure operation. 16 it is often no loss of generality if in the study of the integral closure and dependence we only consider integral domains. There are a few more tools available for integral closure of integral domains. None of the theory developed so far gives a good clue towards deciding when an element in an extension is integral over the base ring, or towards finding equations of integral dependence. In Chapter 15 we discuss some of the computational difficulties: while there is a general algorithm for computing the integral closure of an integral domain, in practice it is often unmanageable.

Download PDF sample

Rated 4.39 of 5 – based on 40 votes