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Multiplicities and equivariant cohomology

dc.contributor.authorLynn, Rebecca E., author
dc.contributor.authorDuflot, Jeanne, advisor
dc.contributor.authorMiranda, Rick, committee member
dc.contributor.authorHulpke, Alexander, committee member
dc.contributor.authorIyer, Hariharan K., committee member
dc.date.accessioned2007-01-03T05:44:50Z
dc.date.available2007-01-03T05:44:50Z
dc.date.issued2010
dc.descriptionDepartment Head: Gerhard Dangelmayr.
dc.description.abstractThe aim of this paper is to address the following problem: how to relate the algebraic definitions and computations of multiplicity from commutative algebra to computations done in the cohomology theory of group actions on manifolds. Specifically, this paper is concerned with applications of commutative algebra to the study of cohomology rings arising from group actions on manifolds, in the way that Quillen initiated. This paper synthesizes two distinct areas of pure mathematics (commutative algebra and cohomology theory) and two ways of computing multiplicities in order to link them. In order to accomplish this task, a discussion of commutative algebra will be followed by a discussion of cohomology theory. A link between commutative algebra and cohomology theory will be presented, followed by its application to a significant example. In commutative algebra, we discuss graded rings, Pioncaré Series, dimension, and multiplicities. Whereas the theory for multiplicities has been developed for local rings, we give an exposition of the theory for graded rings. Several definitions for dimension will be presented, and it will be proven that all of these distinct definitions are equal. The basic properties of multiplicities will be introduced, and a brief discussion of a classical multiplicity in commutative algebra, the Samuel multiplicity, will be presented. Then, Maiorana's C-multiplicity will be defined, and a relationship between all of these multiplicities will be observed. In cohomology theory, we address smooth actions of finite groups on manifolds. As a part of this study in cohomology theory, we will consider group actions on topological spaces and the Borel construction (equivariant cohomology), completing this part of the paper with a discussion of smooth (or differentiable) actions, setting some notation necessary for our discussion of Maiorana's results, which inspire some of our main theorems, but on which we do not rely in this dissertation. Following the treatments of commutative algebra and cohomology theory, we present one of Quillen's main results without proof, linking these two distinct areas of pure mathematics. Quillen's work results in a formula for finding the multiplicity of the equivariant cohomology of a compact G-manifold with G a compact Lie group. We apply these results to the compact G-manifold U/S, where G (a compact Lie group) is embedded in a unitary group U=U(n) and S=S(n) is the diagonal p-torus of rank n in U(n), resulting in a nice topological formula for computing multiplicities. Finally, we end the paper with a proposal for future research.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierLynn_colostate_0053A_10024.pdf
dc.identifierETDF2010100003MATH
dc.identifier.urihttp://hdl.handle.net/10217/39043
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.titleMultiplicities and equivariant cohomology
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineMathematics
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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