Digital Commons Network^™

Homological Characterizations Of Quasi-Complete Intersections, Jason M. Lutz

Department of Mathematics: Dissertations, Theses, and Student Research

Let R be a commutative ring, (f) an ideal of R, and E = K(f; R) the Koszul complex. We investigate the structure of the Tate construction T associated with E. In particular, we study the relationship between the homology of T, the quasi-complete intersection property of ideals, and the complete intersection property of (local) rings.

Advisers: Luchezar L. Avramov and Srikanth B. Iyengar

Management Of Invasive Species Using Optimal Control Theory, Christina J. Edholm

Department of Mathematics: Dissertations, Theses, and Student Research

In my dissertation I will discuss the use of optimal control theory to determine management strategies for an invasive species. I focus on a Diaprepes Root Weevil, which is an invasive species having a substantial negative impact on citrus tree growth in regions such as Florida and California. At the larva stage of the life cycle Diaprepes Root Weevils cause destruction of citrus trees at the root level resulting in loss of citrus crops. This detrimental effect for farmers motivates research into how to minimize the economic loss due to the Diaprepes Root Weevil. For my work, I use optimal …

Applications Of Discrete Mathematics For Understanding Dynamics Of Synapses And Networks In Neuroscience, Caitlyn Parmelee

Department of Mathematics: Dissertations, Theses, and Student Research

Mathematical modeling has broad applications in neuroscience whether we are modeling the dynamics of a single synapse or the dynamics of an entire network of neurons. In Part I, we model vesicle replenishment and release at the photoreceptor synapse to better understand how visual information is processed. In Part II, we explore a simple model of neural networks with the goal of discovering how network structure shapes the behavior of the network.

Vision plays an important role in how we interact with our environments. To fully understand how visual information is processed requires an understanding of the way signals are …

Bridge Spectra Of Cables Of 2-Bridge Knots, Nicholas John Owad

Department of Mathematics: Dissertations, Theses, and Student Research

We compute the bridge spectra of cables of 2-bridge knots. We also give some results about bridge spectra and distance of Montesinos knots.

Advisors: Mark Brittenham and Susan Hermiller

Adian Inverse Semigroups, Muhammad Inam

Department of Mathematics: Dissertations, Theses, and Student Research

The class of Adian semigroups and Adian groups was first introduced and studied by S. I. Adian in 1966. We introduce the notion of Adian inverse semigroups with the hope that the study of these objects may help in resolving some of the remaining open questions about Adian semigroups and Adian groups. We first prove that Adian inverse semigroups are E-unitary. We then prove that if is a finitely presented Adian inverse semigroup which satisfies the property that the Schützenberger complex of each positive word X⁺ over the presentation is finite, then the Schützenberger complex of every word …

A Caputo Boundary Value Problem In Nabla Fractional Calculus, Julia St. Goar

Department of Mathematics: Dissertations, Theses, and Student Research

Boundary value problems have long been of interest in the continuous differential equations context. However, with the advent of new areas like Nabla Fractional Calculus, we may consider such problems in new contexts. In this work, we will consider several right focal boundary value problems, involving a Caputo fractional difference operator, in the Nabla Fractional Calculus context. Properties of the Green's functions for each of these boundary value problems will be investigated and, in the case of a particular boundary value problem, used to establish the existence of positive solutions to a nonlinear version of the boundary value problem.

Adviser: …

Stable Local Cohomology And Cosupport, Peder Thompson

Department of Mathematics: Dissertations, Theses, and Student Research

This dissertation consists of two parts, both under the overarching theme of resolutions over a commutative Noetherian ring R. In particular, we use complete resolutions to study stable local cohomology and cotorsion-flat resolutions to investigate cosupport.

In Part I, we use complete (injective) resolutions to define a stable version of local cohomology. For a module having a complete injective resolution, we associate a stable local cohomology module; this gives a functor to the stable category of Gorenstein injective modules. We show that this functor behaves much like the usual local cohomology functor. When there is only one non-zero local cohomology …

Cohen-Macaulay Dimension For Coherent Rings, Rebecca Egg

Department of Mathematics: Dissertations, Theses, and Student Research

This dissertation presents a homological dimension notion of Cohen-Macaulay for non-Noetherian rings which reduces to the standard definition in the case that the ring is Noetherian, and is inspired by the homological notion of Cohen-Macaulay for local rings developed by Gerko. Under this notion, both coherent regular rings (as defined by Bertin) and coherent Gorenstein rings (as defined by Hummel and Marley) are Cohen-Macaulay.

This work is motivated by Glaz's question regarding whether a notion of Cohen-Macaulay exists for coherent rings which satisfies certain properties and agrees with the usual notion when the ring is Noetherian. Hamilton and Marley gave …

Rigidity Of The Frobenius, Matlis Reflexivity, And Minimal Flat Resolutions, Douglas J. Dailey

Department of Mathematics: Dissertations, Theses, and Student Research

Let R be a commutative, Noetherian ring of characteristic p >0. Denote by f the Frobenius endomorphism, and let R^(e) denote the ring R viewed as an R-module via f^e. Following on classical results of Peskine, Szpiro, and Herzog, Marley and Webb use flat, cotorsion module theory to show that if R has finite Krull dimension, then an R-module M has finite flat dimension if and only if Tor_i^R(R^(e),M) = 0 for all i >0 and infinitely many e >0. Using methods involving the derived category, we show that one only needs vanishing for dim R +1 consecutive values of …