Some notes on the multiplicative order of $$\alpha + \alpha ^{-1}$$α+α-1 in finite fields of characteristic two

Periodica Mathematica Hungarica - In this paper we prove some results on the possible multiplicative order of $$\alpha + \alpha ^{-1}$$ when $$\alpha $$ is a non-zero element of a finite field of...     

Asymptotic Distributions of Zeros of Quadratic Hermite–Pade Polynomials Associated with the Exponential Function

The asymptotic distributions of zeros of the quadratic Hermite--Pad\'{e} polynomials $p_{n},q_{n},r_{n}\in{\cal P}_{n}$ associated with the exponential function are studied for $n\rightarrow\infty$. The polynomials are defined by the relation $$(*)\qquad p_{n}(z)+q_{n}(z)e^{z}+r_{n}(z)e^{2z}=O(z^{3n+2})\qquad\mbox{as} \quad z\rightarrow0,$$ and they form the basis for quadratic Hermite--Pad\'{e} approximants to $e^{z}$. In order to achieve a differentiated picture of the asymptotic behavior of the zeros, the independent variable $z$ is rescaled in such a way that all zeros of the polynomials $p_{n},q_{n},r_{n}$ have finite cluster points as $n\rightarrow\infty$. The asymptotic relations, which are proved, have a precision that is high enough to distinguish the positions of individual zeros. In addition to the zeros of the polynomials $p_{n},q_{n},r_{n}$, also the zeros of the remainder term of (*) are studied. The investigations complement asymptotic results obtained in [17].     

Voronovskaja’s Theorem and Iterations for Complex Bernstein Polynomials in Compact Disks

In this paper, firstly we prove the Voronovskaja’s convergence theorem for complex Bernstein polynomials in compact disks in , centered at origin, with quantitative estimates of this convergence. Secondly, we study the approximation properties of the iterates of complex Bernstein polynomials and we prove that they preserve in the unit disk (beginning with an index) the univalence, starlikeness, convexity and spirallikeness. Received: May 5, 2007 Revised: September 14, 2007 and November 11, 2007 Accepted: November 26, 2007     

Type II Codes over $$\mathbb{Z}/2k\mathbb{Z}$$, Invariant Rings and Theta Series

We consider type II codes over finite rings . It is well-known that their gth complete weight enumerator polynomials are invariant under the action of a certain finite subgroup of , which we denote H_k,g. We show that the invariant ring with respect to H_k,g is generated by such polynomials. This is carried out by using some closely related results concerning theta series and Siegel modular forms with respect to .     

On sums of polynomial-type exceptional units in $$\varvec{\mathbb {Z}}/\varvec{n\mathbb {Z}}$$Z/nZ

A unit u in a commutative ring with unity R is called exceptional if $$u-1$$ is also a unit. We introduce the notion of a polynomial version of this (abbreviated as $$f\hbox {-exunits}$$) for any $$f(X) \in \mathbb {Z}[X]$$. We find the number of representations of a non-zero element of $$\mathbb {Z}/n\mathbb {Z}$$ as a sum of two f-exunits for an infinite family of polynomials f of each degree $$\ge 1$$. We also derive the exact formulae for certain infinite families of linear and quadratic polynomials. This generalizes a result proved by Sander (J Number Theory 159:1–6, 2016).     

Using permutation rational functions to obtain permutation arrays with large hamming distance

Designs, Codes and Cryptography - We consider permutation rational functions (PRFs), V(x)/U(x), where both V(x) and U(x) are polynomials over a finite field $$\mathbb {F}_q$$ . Permutation rational...     

The Krzyz Problem and Polynomials with Zeros on the Unit Circle

Let $ \Pi_{n,M} $ be the class of all polynomials $ p(z) = \sum _{0}^{n} a_{k}z^{k} $ of degree n which have all their zeros on the unit circle $ |z| = 1$ , and satisfy $ M = \max _{|z| = 1}|\,p(z)| $ . Let $ \mu _{k,n} = \sup _{p\in \Pi _{n,M}} |a_{k}| $ . Saff and Sheil-Small asked for the value of $\overline {\lim }_{n\rightarrow \infty }\mu _{k,n} $ . We find an equivalence between this problem and the Krzyz problem on the coefficients of bounded non-vanishing functions. As a result we compute $$ \overline {\lim }_{n\rightarrow \infty }\mu _{k,n} = {{M} \over {e}}\quad {\rm for}\ k = 1,2,3,4,5.$$ We also obtain some bounds for polynomials with zeros on the unit circle. These are related to a problem of Hayman.     

On Kantorovich-Stieltjes operators

Let ν be a finite Borel measure on[0,1]The Kantorovich-Stieltjes polynomials are de-fined byK_n ν=(n+1)N_(k,n)(nN),where N_(k,n)(x)=x~k(1-x)~(n-k)(x[0,1],k=1,2,…,n)are the basic Bernsteinpolynomials and I_(k,n):=[k/(n+1),(k+1)/(n+1)](k=0,1,…,n;nN).We prove that the maximaloperator of the sequence(K_n)is of weak type and the sequence of polynomials(K_n ν)con-verges a.e.on[0,1]to the Radon-Nikodym derivative of the absolutely continuous part of     

The Fitting submodule

Let H be a finite group, a field and V a finite dimensional H-module. We introduce the Fitting submodule F_V (H), an H submodule of V which has properties similar to the generalized Fitting subgroup of a finite group. Received: 26 August 2005     

A Remark on the Arcsine Distribution and the Hilbert transform

Journal of Fourier Analysis and Applications - It is known that if $$(p_n)_{n \in \mathbb {N}}$$ is a sequence of orthogonal polynomials in $$L^2([-1,1], w(x)dx)$$ , then the roots are distributed...     

Explicit factorizations of cyclotomic polynomials over finite fields

Let q be a prime power and let \({\mathbb {F}}_q\) be a finite field with q elements. This paper discusses the explicit factorizations of cyclotomic polynomials over \(\mathbb {F}_q\). Previously, it has been shown that to obtain the factorizations of the \(2^{n}r\)th cyclotomic polynomials, one only need to solve the factorizations of a finite number of cyclotomic polynomials. This paper shows that with an additional condition that \(q\equiv 1 \pmod p\), the result can be generalized to the \(p^{n}r\)th cyclotomic polynomials, where p is an arbitrary odd prime. Applying this result we discuss the factorization of cyclotomic polynomials over finite fields. As examples we give the explicit factorizations of the \(3^{n}\)th, \(3^{n}5\)th and \(3^{n}7\)th cyclotomic polynomials.     

Multilinear Exponential Sums in Prime Fields Under Optimal Entropy Condition on the Sources

The main result of this paper is an exponential sum bound in prime fields for multilinear expressions of the type under nearly optimal conditions on . It provides the expected generalization of the well-known inequality for r = 2. We also establish a new result on Gauss sums for multiplicative subgroups H of , obtaining a nontrivial estimate provided . This is a further improvement on [BGK]. Received: May 2007, Revision: October 2007, Accepted: October 2007     

Quasi-locally finite polynomial endomorphisms

If F is a polynomial endomorphism of , let denote the field of rational functions such that . We will say that F is quasi-locally finite if there exists a nonzero such that p(F) = 0. This terminology comes out from the fact that this definition is less restrictive than the one of locally finite endomorphisms made in Furter, Maubach (J Pure Appl Algebra 211(2):445–458, 2007). Indeed, F is called locally finite if there exists a nonzero such that p(F) = 0. In the present paper, we show that F is quasi-locally finite if and only if for each the sequence is a linear recurrent sequence. Therefore, this notion is in some sense natural. We also give a few basic results on such endomorphisms. For example: they satisfy the Jacobian conjecture.     

Asymptotic Normality for Non-linear Functionals of Non-causal Linear Processes with Summable Weights

Let be a non-causal linear process with weights a_js satisfying certain summability conditions, and the iid sequence of innovation {_i} having zero mean and finite second moment. For a large class of non-linear functional K which includes indicator functions and polynomials, the present paper develops the central limit theorem for the partial sums      

Universal Relations in Asymptotic Formulas for Orthogonal Polynomials

Functional Analysis and Its Applications - Orthogonal polynomials $$P_{n}(\lambda)$$ are oscillating functions of $$n$$ as $$n\to\infty$$ for $$\lambda$$ in the absolutely continuous spectrum of...     

The zero set $$\Lambda $$ of exponential polynomials and the Riesz property of its exponential system $$E_{\Lambda }$$ in $$L^2(0,T)$$

Archiv der Mathematik - Consider the class of exponential polynomials of the form $$\begin{aligned} f(z)=\sum _{n=0}^{N}\left( \sum _{k=0}^{m_n}c_{n,k}z^k\right) e^{h_n z}, \qquad 0=h_0<...     

Polynomial Interpolation of the Discrete Logarithm

Recently, Coppersmith and Shparlinski proved several results on the interpolation of the discrete logarithm in the finite prime field by polynomials modulo p and modulo p-1, respectively. In this paper most of these results are extended to arbitrary .     

Lévy White Noise Calculus Based on Interaction Exponents

Consider the Lévy white noise space where is the space of Schwartz tempered distributions over and μ is a Lévy white noise measure lifted from a one-dimensional infinitely divisible distribution with finite moments. The classical polynomials of Meixner's type are distinguished through a special form of their generating functions. By lifting the generating function of Meixner orthogonal polynomials, we construct the renormalization kernels explicitly in a unified way. Moreover, we define inner products in n-particle spaces in terms of traces on the ‘diagonals’ and obtain a unified explicit chaotic representation of Lévy–Meixner white noise functionals in terms of interacting Fock spaces. The interacting feature is completely determined by a function g which is referred to as ‘interaction exponent’. This method enables us to easily recapture the general form of Lévy–Meixner field operators. ★Project 10171035 and 10401011 Supported by NSFC.     

On hyperbolicity cones associated with elementary symmetric polynomials

Elementary symmetric polynomials can be thought of as derivative polynomials of . Their associated hyperbolicity cones give a natural sequence of relaxations for . We establish a recursive structure for these cones, namely, that the coordinate projections of these cones are themselves hyperbolicity cones associated with elementary symmetric polynomials. As a consequence of this recursion, we give an alternative characterization of these cones, and give an algebraic characterization for one particular dual cone associated with together with its self-concordant barrier functional.     

Exponential Polynomials as Solutions of Differential-Difference Equations of Certain Types

Mediterranean Journal of Mathematics - We consider the exponential polynomials solutions of non-linear differential-difference equation $${f(z)^{n}+q(z)e^{Q(z)}f^{(k)}(z+c) = P(z)}$$ , where q(z),...