Physical Sciences and Mathematics Commons^™

Hartley´S Theorem On Representations Of The General Linear Groups And Classical Groups, A. E. Zalesski

Turkish Journal of Mathematics

We suggest a new proof of Hartley's theorem on representations of the general linear groups GL_n(K) where K is a field. Let H be a subgroup of GL_n(K) and E the natural GL_n(K)-module. Suppose that the restriction E _H of E to H contains a regular KH-module. The theorem asserts that this is then true for an arbitrary GL_n(K)-module M provided dim M>1 and H is not of exponent 2. Our proof is based on the general facts of representation theory of algebraic groups. In addition, we provide partial generalizations of Hartley's theorem to other classical groups.

Black Box Groups, Şükrü Yalçinkaya

Turkish Journal of Mathematics

We propose a uniform approach for recognizing all black box groups of Lie type which is based on the analysis of the structure of the centralizers of involutions. Our approach can be viewed as a computational version of the classification of the finite simple groups. We present an algorithm which constructs a long root SL_2(q)-subgroup in a finite simple group of Lie type of odd characteristic, then we use the Aschbacher's ``Classical Involution Theorem'' as a model in the recognition algorithm and we construct all root SL_2(q)-subgroups corresponding to the nodes in the extended Dynkin diagram, that is, we construct …

New Integral Inequalities For Iterated Integrals With Applications, Ravi P. Agarwal, Cheonseoung Ryoo

Mathematics and System Engineering Faculty Publications

Some new nonlinear retarded integral inequalities of Gronwall type are established. These inequalities can be used as basic tools in the study of certain classes of integrodifferential equations.

Reaction-Diffusion In Nonsmooth And Closed Domains, Ugur G. Abdulla

Mathematics and System Engineering Faculty Publications

We investigate the Dirichlet problem for the parabolic equation in a nonsmooth and closed domain possibly formed with irregular surfaces and having a characteristic vertex point. Existence, boundary regularity, uniqueness, and comparison results are established. The main objective of the paper is to express the criteria for the well-posedness in terms of the local modulus of lower semicontinuity of the boundary manifold. The two key problems in that context are the boundary regularity of the weak solution and the question whether any weak solution is at the same time a viscosity solution.

Philos-Type Oscillation Criteria For Second Order Half-Linear Dynamic Equations On Time Scales, Ravi P. Agarwal, Donal O'Regan, Samir H. Saker

Mathematics and System Engineering Faculty Publications

In this paper we establish some oscillation theorems for the second order half-linear dynamic equation (r(t)(x Δ(t) γ) Δ + p(t)x γ(t) = 0, ∈ [a,b], on time scales. Special cases of our results include some well-known oscillation results for second-order differential and half-linear differential equations. Our results are new for difference, generalized difference and q difference half-linear equations. Copyright © 2007 Rocky Mountain Mathematics Consortium.

Restricted Colored Permutations And Chebyshev Polynomials, Eric S. Egge

Faculty Work

Several authors have examined connections between restricted permutations and Chebyshev polynomials of the second kind. In this paper we prove analogues of these results for colored permutations. First we define a distinguished set of length two and length three patterns, which contains only 312 when just one color is used. Then we give a recursive procedure for computing the generating function for the colored permutations which avoid this distinguished set and any set of additional patterns, which we use to find a new set of signed permutations counted by the Catalan numbers and a new set of signed permutations counted …

Continued Fractions With Multiple Limits, Douglas Bowman, James Mclaughlin

Mathematics Faculty Publications

For integers m ≥ 2, we study divergent continued fractions whose numerators and denominators in each of the m arithmetic progressions modulo m converge. Special cases give, among other things, an infinite sequence of divergence theorems, the first of which is the classical Stern-Stolz theorem. We give a theorem on a class of Poincar´e type recurrences which shows that they tend to limits when the limits are taken in residue classes and the roots of their characteristic polynomials are distinct roots of unity. We also generalize a curious q-continued fraction of Ramanujan’s with three limits to a continued fraction with …

Population Modeling By Differential Equations, Hui Luo

Theses, Dissertations and Capstones

A general model for the population of Tibetan antelope is constructed. The present model shows that the given data is reasonably logistic. From this model the extinction of antelopes in China is predicted if we don’t consider the effects of humans on the population. Moreover, this model shows that the population is limited. A projected limiting number is given by this model. Some typical mathematical models are introduced such as exponential model and logistic model. The solutions of those models are analyzed.

Bounds And Comparisons For Weighted Renewal-Type Integral Equations, Broderick O. Oluyede

Department of Mathematical Sciences Faculty Publications

In this note, inequalities and bounds for weighted renewal-type integral equations are presented. Some upper and lower bounds for the weighted renewal-type integral equations with monotone weight functions are derived. Some upper and lower bounds for the weighted renewal-type equations with monotone weight functions are derived. Bounds for the difference between two weighted renewal functions as well between the parent and weighted renewal functions are obtained in terms of the parent renewal reliability functions and their first and second moments. Relations for renewal-type integrals of the ruin probability are presented. Some inequalities, bounds and convergence results are also established.

Complex Symmetric Operators And Applications Ii, Stephan Ramon Garcia, Mihai Putinar

Pomona Faculty Publications and Research

A bounded linear operator T on a complex Hilbert space H is called complex symmetric if T = CT*C, where C is a conjugation (an isometric, antilinear involution of H). We prove that T = CJ|T|, where J is an auxiliary conjugation commuting with |T| = √{T*T). We consider numerous examples, including the Poincaré-Neumann singular integral (bounded) operator and the Jordan model operator (compressed shift). The decomposition T = CJ|T| also extends to the class of unbounded C-self adjoint operators, originally introduced by Glazman. In this context, it provides a method for estimating the norms …

Towards The Computation Of The Convex Hull Of A Configuration From Its Corresponding Separating Matrix, Elie Feder, David Garber

Publications and Research

In this paper we cope with the following problem compute the size of the convex hull of a configuration C where the given data is the number of separating lines between any two points of the configuration (where the lines are generated by pairs of other points of the configuration)

We give an algorithm for the case that the convex hull is of size 3 and a partial algorithm and some directions for the case that the convex hull is of size bigger than 3.

A Transform Method In Discrete Fractional Calculus, Ferhan M. Atici, Paul W. Eloe

Mathematics Faculty Publications

We begin with an introduction to a calculus of fractional finite differences. We extend the discrete Laplace transform to develop a discrete transform method. We define a family of finite fractional difference equations and employ the transform method to obtain solutions.

A Comparison Of Three Topologies On Ordered Sets, Joe Mashburn

Mathematics Faculty Publications

We introduce two new topologies on ordered sets: the way below topology and weakly way below topology. These are similar in definition to the Scott topology, but are very different if the set is not continuous. The basic properties of these three topologies are compared. We will show that while domain representable spaces must be Baire, this is not the case with the new topologies.

2007 (Winter), University Of Dayton. Department Of Mathematics

Colloquia

Abstracts of the talks given at the 2007 Winter Colloquium.

Wild Partitions And Number Theory, David P. Roberts

Mathematics Publications

We introduce the notion of wild partition to describe in combinatorial language an important situation in the theory of p-adic fields. For Q a power of p, we get a sequence of numbers λ_Q,n counting the number of certain wild partitions of n. We give an explicit formula for the corresponding generating function Λ_Q(x) = Σλ_Q,nx^_n and use it to show that λ^1/n _Q,n tends to Q^1/(p-1). We apply this asymptotic result to support a finiteness conjecture about number fields. Our finiteness conjecture …

On The Direction Of Pitchfork Bifurcation, Xiaojie Hou, Philip Korman, Yi Li

Mathematics and Statistics Faculty Publications

We present an algorithm for computing the direction of pitchfork bifurcation for two-point boundary value problems. The formula is rather involved, but its computational evaluation is quite feasible. As an application, we obtain a multiplicity result.

On The Exact Multiplicity Of Solutions For Boundary-Value Problems Via Computing The Direction Of Bifurcations, Joaquin Riviera, Yi Li

Mathematics and Statistics Faculty Publications

No abstract provided.

A Comparison Of Graphical Methods For Assessing The Proportional Hazards Assumptions In The Cox Model, Inger Persson, Harry J. Khamis

Mathematics and Statistics Faculty Publications

Six graphical procedures to check the assumption of proportional hazards for the Cox model are described and compared. A new way of comparing the graphical procedures using a Kolmogorov-Smirnov like maximum deviation criterion for rejection is derived for each procedure. The procedures are evaluated in a simulation study under proportional hazards and five different forms of nonproportional hazards: (1) increasing hazards, (2) decreasing hazards, (3) crossing hazards, (4) diverging hazards, and (5) nonmonotonic hazards. The procedures are compared in the two-sample case corresponding to two groups with different hazard functions. None of the procedures under consideration require partitioning of the …

Projective-Planar Signed Graphs And Tangled Signed Graphs, Dan Slilaty

Mathematics and Statistics Faculty Publications

A projective-planar signed graph has no two vertex-disjoint negative circles. We prove that every signed graph with no two vertex-disjoint negative circles and no balancing vertex is obtained by taking a projective-planar signed graph or a copy of −K5" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">−K5 and then taking 1-, 2-, and 3-sums with balanced signed grap

Critical Mathematics Pedagogy: Transforming Teachers’ Practices, David W. Stinson, Carla R. Bidwell, Christopher C. Jett, Ginny C. Powell, Mary M. Thurman

Middle-Secondary Education and Instructional Technology Faculty Publications

This study reports the effects of a graduate-level mathematics education course that focused on critical theory and teaching for social justice on the pedagogical philosophies and practices of three mathematics teachers (middle, high school, and 2-year college). The study employed Freirian participatory research methodology; in fact, the participants were not only co-researchers, but also co-authors of the study. Data collection included reflective essays, journals, and “storytelling”; data analysis was a combination of textual analysis and autoethnography. The findings report that the teachers believed that the course provided not only a new language but also a legitimization to transform their pedagogical …

What Is Mathematics?: Teachers Exploring The Philosophy Of Mathematics, Kimberly White-Fredette, David W. Stinson

Middle-Secondary Education and Instructional Technology Faculty Publications

No abstract provided.

Some Observations On Khovanskii's Matrix Methods For Extracting Roots Of Polynomials, James Mclaughlin, B. Sury

Mathematics Faculty Publications

In this article we apply a formula for the n-th power of a 3×3 matrix (found previously by the authors) to investigate a procedure of Khovanskii’s for finding the cube root of a positive integer. We show, for each positive integer α, how to construct certain families of integer sequences such that a certain rational expression, involving the ratio of successive terms in each family, tends to α 1/3 . We also show how to choose the optimal value of a free parameter to get maximum speed of convergence. We apply a similar method, also due to Khovanskii, to a …

Ramanujan And Extensions And Contractions Of Continued Fractions, James Mclaughlin, Nancy Wyshinski

Mathematics Faculty Publications

If a continued fraction K∞n=1an/bn is known to converge but its limit is not easy to determine, it may be easier to use an extension of K∞n=1an/bn to find the limit. By an extension of K∞n=1an/bn we mean a continued fraction K∞n=1cn/dn whose odd or even part is K∞n=1an/bn. One can then possibly find the limit in one of three ways: (i) Prove the extension converges and find its limit; (ii) Prove the extension converges and find the limit of the other contraction (for example, the odd part, if K∞n=1an/bn is the even part); (ii) Find the limit of the …

K-41 Optimized Approximate Deconvolution Models, William Layton, Iuliana Stanculescu

Mathematics Faculty Articles

If the Navier-Stokes equations are averaged with a local, spacial convolution type filter, φ = gδ ∗ φ , the resulting system is not closed due to the filtered nonlinear term uu. An approximate deconvolution operator D is a bounded linear operator which satisfies

u = D(u) + O(δ α ),

where δ is the filter width and α ≥ 2. Using a deconvolution operator as an approximate filter inverse yields the closure

uu = D(u)D(u) + O(δ α ).

We derive optimal approximate deconvolution models for 3D turbulence. Specifically, we find the optimal parameters that minimize the time averaged …

Projectional Entropy In Higher Dimensional Shifts Of Finite Type, Aimee S. A. Johnson, S. Kass, K. M. Madden

Mathematics & Statistics Faculty Works

Any higher dimensional shift space (X, ℤᵈ) contains many lower dimensional shift spaces obtained by projection onto r-dimensional sublattices L of ℤᵈ where r < d. We show here that any projectional entropy is bounded below by the ℤᵈ entropy and, in the case of certain shifts of finite type satisfying a mixing condition, equality is achieved if and only if the shift of finite type is the infinite product of a lower dimensional projection.

Symmetry And Specializability In The Continued Fraction Expansions Of Some Infinite Products, James Mclaughlin

Mathematics Faculty Publications

Let f(x) ∈ Z[x]. Set f0(x) = x and, for n ≥ 1, define fn(x) = f(fn−1(x)). We describe several infinite families of polynomials for which the infinite product Y∞ n=0 ( 1 + 1 fn(x) ) has a specializable continued fraction expansion of the form S∞ = [1; a1(x), a2(x), a3(x), . . . ], where ai(x) ∈ Z[x] for i ≥ 1. When the infinite product and the continued fraction are specialized by letting x take integral values, we get infinite classes of real numbers whose regular continued fraction expansion is predictable. We also show that, under some …

Some More Long Continued Fractions, I, James Mclaughlin, Peter Zimmer

Mathematics Faculty Publications

In this paper we show how to construct several infinite families of polynomials D(¯x, k), such that p D(¯x, k) has a regular continued fraction expansion with arbitrarily long period, the length of this period being controlled by the positive integer parameter k. We also describe how to quickly compute the fundamental units in the corresponding real quadratic fields.

Some Properties Of The Distribution Of The Numbers Of Points On Elliptic Curves Over A Finite Prime Field, Saiying He, James Mclaughlin

Mathematics Faculty Publications

Let p ≥ 5 be a prime and for a, b ∈ Fp, let Ea,b denote the elliptic curve over Fp with equation y 2 = x 3 + a x + b. As usual define the trace of Frobenius ap, a, b by #Ea,b(Fp) = p + 1 − ap, a, b. We use elementary facts about exponential sums and known results about binary quadratic forms over finite fields to evaluate the sums P t∈Fp ap, t, b, P t∈Fp ap, a, t, Pp−1 t=0 a 2 p, t, b, Pp−1 t=0 a 2 p, a, t and Pp−1 …

Characterizations Of Pseudo-Codewords Of Ldpc Codes, Ralf Koetter, Wen-Cheng W. Li, Pascal O. Vontobel, Judy L. Walker

Department of Mathematics: Faculty Publications

An important property of high-performance, low complexity codes is the existence of highly efficient algorithms for their decoding. Many of the most efficient, recent graph-based algorithms, e.g. message passing algorithms and decoding based on linear programming, crucially depend on the efficient representation of a code in a graphical model. In order to understand the performance of these algorithms, we argue for the characterization of codes in terms of a so called fundamental cone in Euclidean space which is a function of a given parity check matrix of a code, rather than of the code itself. We give a number of …

On Groups Of Homological Dimension One, Jonathan Cornick

Publications and Research

It has been conjectured that the groups of homological dimension one are precisely the nontrivial locally free groups. Some algebraic, geometric and analytic properties of any potential counter example to the conjecture are discussed.