Proposals

Below are some proposals for talks from the past (and current). By clicking on the ID number, more details are shown. By default, these are sorted chronologically (recent first) and by then by last name. The data can be sorted by alternate means by using the links at the top right, each allowing ascending or descending orders.

Displaying 381-400 of 471 results.
ID: 166
Year: 2006
Name: Brian Birgen
Institution: Wartburg College
Subject area(s): Recreational Mathematics / Group Theory
Title of Talk: Subgroups of the Rubik's Group

Abstract: The set of possible arrangements of the Rubik's Cube forms a group with 4*10^19 elements. We will locate some well known groups which occur as subgroups of the Rubik's group and begin to understand the source of some of the complexities in understanding the Rubik's group.
ID: 165
Year: 2006
Name: Luz De Alba
Institution: Drake University
Subject area(s): Linear Algebra, Matrix Theory, Graph Theory
Title of Talk: Comparison of P-matrix completions with Q-matrix completions.

Abstract: A P-matrix is a real square matrix, in which the determinant of every principal submatrix is positive. A Q-matrix is one in which the sum of the determinants of principal submatrices of the same size is positive. Clearly every P-matrix is a Q-matrix. A partial P-matrix is a matrix in which some entries are specified while others are not known, and every fully specified principal submatrix has positive determinant. The P-matrix completion problem asks the question: "Which partial P-matrices can be completed to a P-matrix?" In this talk we give the definition of partial Q-matrix, and compare the Q-matrix completion problem to the P-matrix completion problem. We also discuss some partial answers to the Q-completion problem.
ID: 163
Year: 2006
Name: Justin From
Institution: Central College
Subject area(s):
Title of Talk: The Polynomial Root Squeezing Theorem

Abstract: Polynomials are one of the most widely used functions in mathematics, yet there are surprisingly many unanswered questions about their properties. This talk will present an innovative new idea referred to as the Polynomial Root Squeezing Theorem which shows that squeezing two of a polynomial
ID: 162
Year: 2006
Name: Giovanna Llosent
Institution: University of Iowa
Subject area(s): Modular Representation Theory
Title of Talk: The stable endomorphism group of non-simple string modules over a very particular finite dimensional algebra.

Abstract: Let A be a finite dimensional algebra over an algebraic closed field k of characteristic 2 with a quiver representation and relations. Consider all non-simple string modules for this algebra which do not lie in the Auslander-Reiten component of the simple modules. Is there a non-simple string module M for which the group of stable endomorphisms is isomorphic to k? Under the hypothesis above we were able to prove that the underlying string S of the string module M has a substring S' and there is an endomorphism that does not factor through a projective A-module and lies in S'. The maximun lenght of the underlying string of a string module needed for completing the study of all stable endomorphism groups of non-simple string modules was 17. In particular, the cases needed for complete generalization are 54.
ID: 161
Year: 2006
Name: Jacob Manske
Institution: Iowa State University
Subject area(s): Philosophy of Mathematics
Title of Talk: Hey, Kids! Improve Your Theorems! Add Superfluous Hypotheses!

Abstract: In spite of the fact that we tell students not to assume what they are trying to prove, we all must do precisely that. The interesting theorems, then, turn out to be the ones whose tautologous nature is elusive. This will be a philosophical discussion; bellicose debate is encouraged.
ID: 160
Year: 2006
Name: Catherine Gorini
Institution: Maharishi University of Management
Subject area(s):
Title of Talk: Visualizing Linear Algebra with Geometer

Abstract: I will present Sketchpad labs for visualizing the following concepts in linear algebra: Linear transformations and image, range, kernel, and projection. The determinant of a matrix and the orientation-preserving or-reversing property of the corresponding linear transformation. The determinant a matrix to the area of the image of a unit area under the corresponding linear transformation. Eigenvectors and eigenvalues
ID: 159
Year: 2006
Name: WEN ZHOU
Institution: Iowa State University
Subject area(s):
Title of Talk: Chemotactic Collapse in Keller-Segel Equation

Abstract: Chemotaxis phenomenon is one of the most fundamental phenomenons in the biology field. In 1970s, Keller and Segel characterize this phenomenon with two coupled equations. Study on the blow up of the solutions of the this equation is one of the key part of the research on this equation. This short talk will briefly introduce some recent results of the study on this equation, including Nagai, Velazquez, Stevens, Levine, and Hortsman's work, etc.
ID: 158
Year: 2006
Name: Steve Bean
Institution: Cornell College
Subject area(s): math history
Title of Talk: Why does 0! = 1? The evolution of the gamma function

Abstract: The gamma function is typically introduced as an attempt to interpolate the factorial function, but what motivation does one have to do this? After giving a brief overview of the gamma function and its properties--from the modern point of view,--we will talk about the same function from a historical perspective. In particular, we will examine the reasons behind Euler's original formulation of this function.
ID: 157
Year: 2006
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s): Voting Strategies
Title of Talk: Arrow's Hypotheses

Abstract: We prove three consequences of Arrow's Hypotheses. (1) If some of the ballots put x first and the rest put x last, then x has to be either first or last in the group ranking. (2) If the rankings of a with b match the rankings of c with d on each ballot, then the group ranking must also match the ranking of a with b and c with d. (3) The group ranking must match one of the ballots. This material was taken from "Three Brief Proofs of Arrow's Impossibility Theorem" by John Geanakoplos. The point of the talk is to show that the proofs are very elementary. The various strategies for voting are covered in many very elementary texts. Their discussion is directed towards with of the hypotheses the voting strategies violate. This talk shows how the hypotheses can be combined to directly obtain conclusions that do not seem as fundamentally fair as the original hypotheses.
ID: 155
Year: 2006
Name: Di Wu
Institution: Iowa State University
Subject area(s): Computational Biology and Applied Mathematics
Title of Talk: Protein Structure Determination: A Rigid Geometric Build-up Algorithm for Solving a Distance Geometry Problem with Sparse Exact Distance Data

Abstract: Protein Structure Determination: A Rigid Geometric Build-up Algorithm for Solving a Distance Geometry Problem with Sparse Exact Distance Data Di Wu and Zhijun Wu Program on Bioinformatics and Computational Biology Department of Mathematics Iowa State University Ames, Iowa 50011 Abstract. Given a set of distances for certain pairs of atoms in a protein, the coordinates of the atoms and hence the protein structure can then be determined through solving a so-called distance geometry problem. However, it has been proved to be a NP hard problem when only a set of partial distances given. Previously, we used a so-called geometric build-up approach to develop several algorithms for solving the distance geometry problem with a set of sparse distance data. In this method, the coordinates of the atoms in a protein are determined as one atom at a time, with the distances from four base atoms to the atom to be determined. However, the requirement for four base atoms for the unique determination of each atom is sufficient, but unnecessary and even redundant for rigid structural determination. Here we investigate a rigid geometric build-up algorithm, which requires three base atoms instead of four base atoms for the determination of each atom. It could generate rigid structures, even a unique structure for very sparse distance data of a protein eventually. Due to the reflection in the determination for some atoms, this algorithm may also produce multiple structures satisfying given distances. We present the results obtained by using the algorithm for the determination of the structures, which suggests the potential of applying the algorithm to the distance based protein structural modeling.
ID: 154
Year: 2006
Name: Stephen Willson
Institution: Iowa State University
Subject area(s): Graph theory / mathematical biology
Title of Talk: Reconstructing genomes in the presence of hybridizations

Abstract: A homoplasy at a site in the DNA occurs when the value of a character (A, C, G, or T) changes more than once in the evolutionary history. Homoplasies create extra difficulties for reconstructing the evolutionary history of a collection of taxa. Recent interest has grown concerning evolutionary histories that are not described by trees but rather by more general networks that allow for hybridization events. A natural question is, in an idealized situation where homoplasies occur only at hybridization events, whether the characters at the leaves and the root of the network determine the characters at the internal vertices. Mathematically, one has a directed rooted acyclic graph in which the vertices correspond to taxa. At each vertex there is a set of genes. Under appropriate assumptions, the genes at all vertices are determined by the genes at the root and at the leaves.
ID: 153
Year: 2006
Name: Charles Ashbacher
Institution: Mt. Mercy College
Subject area(s): Number theory
Title of Talk: Some Properties of the Smarandache Fitorial and Supplementary Fitorial Functions

Abstract: The Smarandache Fitorial function FI(N) is defined as the product of all the positive integers less than N that are relatively prime to N and the Smarandache Supplementary Fitorial function SFI(N) as the product of all the positive integers less than or equal to N that are not relatively prime to N. It is clear that FI(N) * SFI(N) = N!. These functions are defined in the book
ID: 152
Year: 2006
Name: Kunlun Liu
Institution: Iowa State University
Subject area(s): PDE
Title of Talk: Existence of strong solution for a class of nonlinear parabolic systems

Abstract: This paper deals with the local and global existence of the strong solution for a class of nonlinear parabolic PDEs in the domain [0,T]
ID: 151
Year: 2006
Name: Wolfgang Kliemann
Institution: Iowa State University
Subject area(s): calculus, differential equations, analysis, dynamical systems
Title of Talk: Global Dynamics and Chaos

Abstract: Global Dynamics and Chaos Wolfgang Kliemann Department of Mathematics, Iowa State University, Ames, Iowa 50011, U.S.A. February 27, 2006 Abstract We discuss dynamical systems given by  a time set - in our case the real line R,  a state space M - a compact subset of Rd or a compact metric space,  a continuous map  : R M ��! M with two properties (0; x) = x for all x 2 M (t + s; x) = (t; (s; x)) for all x 2 M, all t; s 2 R. Typical examples are solutions of (time-homogeneous) di
ID: 150
Year: 2006
Name: Joseph Keller
Institution: Iowa State University
Subject area(s): functional analysis
Title of Talk: "Convergence depth": proof of the nonrotation and nontranslation of galaxies

Abstract: HC Arp (Max Planck Inst.) amassed evidence that most large redshift is intrinsic, not due to motion or expansion. WG Tifft (Univ. of Arizona) says that redshift periods, large and small, suggest abandoning the motion/expansion hypothesis altogether. "Convergence depth", a phenomenon studied by this author since 2002, means that the average velocity over successive shells of galaxies, converges in a mere 400 M lt yr, to the apparent velocity ("anisotropy") of the sources of the cosmic microwave background ("CMB"). The shape of the convergence depth curve, and the observed 400 M lt yr period of galaxy distribution, suggest that Hubble's parameter varies sinusoidally along the axis of the CMB anisotropy, with half-period 400 M lt yr. Taylor series extrapolation of the convergence depth curve to the origin, then shows that the velocity of the sun relative to distant galaxies is about equal to its velocity relative to nearby stars. Galaxies neither rotate nor translate. "Dark matter" need not exist. Oort's law is not due to motion. An absolute frame of reference (Maxwell/FitzGerald ether?) is supported. DC Miller (Case Univ.) found that apparent "ether drift" agrees, in its component parallel to Earth's axis, with the solar apex motion, i.e., motion in the extragalactic frame.
ID: 149
Year: 2006
Name: Zhongming WANG
Institution: Iowa State University
Subject area(s):
Title of Talk: computing multivalued velocity and electric field of 1D Euler-Poisson equation

Abstract: We develop a level set method for the computation of multi-valued velocity and electric fields of one-dimensional Euler-Poisson equations. The sys- tem of these equations arises in the semiclassical approximation of Schrodinger- Poisson equations and semiconductor modeling. This method uses an implicit Eulerian formulation in an extended space | called field space, which incorpo- rates both velocity and electric fields into the configuration space. Multi-valued velocity and electric fields are captured through common zeros of two level set functions, which solve a linear homogeneous transport equation in the field space. Numerical examples are presented to validate the proposed level set method.
ID: 148
Year: 2006
Name: Alfredo Villanueva
Institution: University of Iowa
Subject area(s): Differential Geometry
Title of Talk: Prolongations on a Riemannian Manifold

Abstract: Traditionally the method of prolongations is carry out by algebraic manipulations which become very complex, especially in cases of partial differential equations on curved spaces, here we are applying some results from representation theory and differential operators to have a systematic method that allow us to close some overdetermined systems on a Riemannian manifold.
ID: 147
Year: 2006
Name: Scott Wood
Institution: University of Iowa
Subject area(s): Bayesian statistics, spatial statistics, medical geography
Title of Talk: Model Fitting and Selection for County-Level Depression Hospitalization Rates Using Bayesian Statistical Methods

Abstract: Researchers in the health sciences are interested in identifying and modeling the risk factors that are associated with high rates of hospitalization for depression. Being able to identify U.S. counties with high standardized hospitalization rates (SHR) would be useful in allocating federal resources. This project analyzes and critiques three potential Bayesian statistical models that can be implemented using WinBUGS software. Ordinary least squares, Poisson regression, and Bayesian conditional autoregressive (CAR) models are considered in detail. Though each has its advantages and disadvantages, qualitative and quantitative evidence suggest that the Bayesian CAR model is the optimal choice for this data. While a Bayesian CAR model will be shown to account for spatial autocorrelation and Poisson response variables, it was not as reliable as hoped for making accurate predictions at the county level.
ID: 146
Year: 2006
Name: Jeremy Alm
Institution: Iowa State University
Subject area(s): mathematical logic, pedagogy
Title of Talk: Godel Disrobes: a naked approach to incompleteness

Abstract: I propose an alternate approach to the incompleteness theorems via the conceptually simpler \emph{abstract provability systems}, due to Raymond Smullyan. These systems have incompleteness theorems that are easy to prove, and whose hypotheses point to the important features of formal arithmetic.
ID: 145
Year: 2006
Name: Michael Larsen
Institution: Iowa State University
Subject area(s): Statistics, Teaching Statistics
Title of Talk: Teaching Mathematical Probability and Statistics with Internet Applications and R

Abstract: Courses in mathematical statistics can use Internet applications and simulation using the R statistical package to enhance the learning experience. Internet material has been developed for introductory probability and statistics courses and for teaching mathematics at the level of calculus. In order to adapt this material to an intermediate undergraduate probability course, it is necessary to select material to use and incorporate it into lecture, homework assignments, and study problems. The R statistical package is a free software package that can be used for simulation, includes functions related to many probability distributions, and can be used to produce nice graphical displays. Using R in a calculus-based probability course requires writing problems for homework assignments, in-class use, and review that make substantial use of simulation and R