On the linearity of Artin functions

It was proved by Elkik that, under some smoothness conditions, the Artin functions of systems of polynomials over a Henselian pair are bounded above by linear functions. This paper gives a stronger form of this result for the class of excellent Henselian local rings. The linearity of Artin functions of systems of polynomials in one variable is also studied. Explicit calculations of Artin functions of monomials and determinantal ideals are also included.     

The calculus of the trigonometric functions

The trigonometric functions entered “analysis” when Isaac Newton derived the power series for the sine in his De Analysi of 1669. On the other hand, no textbook until 1748 dealt with the calculus of these functions. That is, in none of the dozen or so calculus texts written in England and the continent during the first half of the 18th century was there a treatment of the derivative and integral of the sine or cosine or any discussion of the periodicity or addition properties of these functions. This contrasts sharply with what occurred in the case of the exponential and logarithmic functions. We attempt here to explain why the trigonometric functions did not enter calculus until about 1739. In that year, however, Leonhard Euler invented this calculus. He was led to this invention by the need for the trigonometric functions as solutions of linear differential equations. In addition, his discovery of a general method for solving linear differential equations with constant coefficients was influenced by his knowledge that these functions must provide part of that solution.     

Problem of checking the functional completeness in the class of piecewise parallel functions

The author showed previously that it is possible to implement an arbitrary piecewise parallel function by circuits of linear elements and one nonlinear element implementing the θ-function. Thus, the functional completeness of a particular system of functions in the class of piecewise parallel functions was established. In this paper we consider the same class and study its completeness property for a system of functions whose closures contain all linear functions. We formulate and prove a criterion of functional completeness for such systems in terms of precomplete classes.     

The modular properties and the integral representations of the multiple elliptic gamma functions

We show the modular properties of the multiple “elliptic” gamma functions, which are an extension of those of the theta function and the elliptic gamma function. The modular property of the theta function is known as Jacobi's transformation, and that of the elliptic gamma function was provided by Felder and Varchenko. In this paper, we deal with the multiple sine functions, since the modular properties of the multiple elliptic gamma functions result from the equivalence between two ways to represent the multiple sine functions as infinite products.We also derive integral representations of the multiple sine functions and the multiple elliptic gamma functions. We introduce correspondences between the multiple elliptic gamma functions and the multiple sine functions.     

一类非对称各向同性张量函数导数的不变表示

将Dui和Chen于2004年提出的求解对称各向同性张量函数导数的方法推广到一类满足可交换条件的非对称各向同性张量函数情况,此类函数比以往研究的更具一般性．在有3个不同特征根时,由可交换性引进张量函数相对应的标量函数,进而求得此类非对称各向同性张量函数及其导数的不变表示形式．在2或3重特征根时,利用求极限的办法给出此类张量函数及其导数的表示形式．     

Increasing the security of hash functions

In this paper, we introduce a solution for ensuring data integrity using cryptographic one-way hash functions. The cryptographic security of such hash functions was estimated by us in detail for different kinds of attacks. We propose several new schemes for increasing the security of one-way hash functions without reformation of its internal algorithms. Also we outline schemes with the best speed and security level. We show that the Schneier method of suffix superposition has a serious drawback. In this article, we also suggest the method of constructing collision resistant one-way hash functions from standard well-known hash functions. Therefore, the proposed schemas can be used to upgrade the majority of cryptographic one-way functions, such as MD4, MD5, RIPEMD, SHA, GOST 34 11-94.     

Uniqueness and nonuniqueness of the solution to the problem of determining the source in the heat equation

An initial–boundary value problem for the two-dimensional heat equation with a source is considered. The source is the sum of two unknown functions of spatial variables multiplied by exponentially decaying functions of time. The inverse problem is stated of determining two unknown functions of spatial variables from additional information on the solution of the initial–boundary value problem, which is a function of time and one of the spatial variables. It is shown that, in the general case, this inverse problem has an infinite set of solutions. It is proved that the solution of the inverse problem is unique in the class of sufficiently smooth compactly supported functions such that the supports of the unknown functions do not intersect. This result is extended to the case of a source involving an arbitrary finite number of unknown functions of spatial variables multiplied by exponentially decaying functions of time.     

Some properties of harmonic functions generated by the bergman-whittaker operator

Summary We deduce properties concerning singular curves of harmonic functions generated by the Bergman-Whittaker operator and obtain an analogue of the Eisenstein theorem for a certain class of such harmonic functions. This research was supported in part by the Air Force Office of Scientific Research.     

On the continuity of functions

In this paper, results of a questionnaire about continuity of functions are analysed. The tested students attend Novi Sad grammar school. The aim of this test was to check the student's theoretical and visual knowledge of continuous functions at the end of their high school education. The questions were given with and without the graphs of functions. The main conclusion is that the graph of a function has a significant influence on the students opinion about continuity. Looking at the graphs of functions mostly led to correct answers, but sometimes it causes problems, if it has a break. The idea came from a 1981 paper by Tall and Vinner, where the “concept image” of a continuous functions was examined.     

Wiener's tauberian theorem for spherical functions on the automorphism group of the unit disk

Our main result gives necessary and sufficient conditions, in terms of Fourier transforms, for an ideal in the convolution algebra of spherical integrable functions on the (conformal) automorphism group of the unit disk to be dense, or to have as closure the closed ideal of functions with integral zero. This is then used to prove a generalization of Furstenberg's theorem, which characterizes harmonic functions on the unit disk by a mean value property, and a “two circles” Morera type theorem (earlier announced by Agranovskii). The second author's work was partially supported by the fund for the promotion of research at the Technion-Israel Institute of Technology. The third author's work was partially supported by the Swedish Natural Science Research Council, and by the 1992 Wallenberg Prize from the Swedish Mathematical Society.     

There is no continuous projection from the measurable functions on the square onto the measurable functions on the interval

It is proved that the space of functions constant on vertical lines is not complemented in the space of all measurable functions on the unit square (with the topology of convergence in measure). The analogous results is proved for the space of all measurable functions on the product of two probability spaces, one of which is atomless. This research was partially supported by National Science Foundation grant N.S.F. GP 28577.     

Value distribution of the difference operator

We investigate the value distribution of difference operators for entire functions, and establish a difference analogue of the Brück conjecture for entire functions of order less than 1. This work was supported by the NNSF of China (No. 10671109).     

二维随机变量和谐度量函数及其应用

本文讨论基于二维随机变量递增速度快慢的刻画及描述问题.引入和谐函数的概念,并利用和谐函数对二维随机变量和谐度量指标的定义进行改进,使得对二维随机变量之间和谐关系的研究更进一步.此外,借助于连接函数得到和谐函数的性质和计算公式,并将其应用到具体实例,借助和谐函数的图形进一步验证和谐函数的性质和主要结论.     

Properties of Algebraic Equations on the Set of E-Functions over the Field of Rational Functions

The paper presents several theorems on the linear and algebraic independence of the values at algebraic points of the set of E-functions related by algebraic equations over the field of rational functions, as well as some estimates of the absolute values of polynomials with integer coefficients in the values of such functions. The results are obtained by using the properties of ideals in the ring of polynomials of several variables formed by equations relating the above functions over the field of rational functions.     

A quantitative version of the Dirichlet-Jordan test for double Fourier series

For classes of functions with convergent Fourier series, the problem of estimating the rate of convergence has always been of interest. The classical theorem of Dirichlet and Jordan for functions of bounded variation assures the convergence of their Fourier series, but gives no estimate of the rate of convergence. Such an estimate was first provided by Bojani . Here we consider this problem in the case of functions of two variables that are of bounded variation in the sense of Hardy and Krause. The Dirichlet-Jordan test was first extended by Hardy from single to double Fourier series. Now, we provide a quantitative version of it. We prove our estimate in a greater generality, by introducing the so-called rectangular oscillation of a function of two variables over a rectangle.     

The majorization function and the index of invariant sub spaces in the Bergman spaces

The index of an invariant subspace ℳ of a Banach space of analytic functions in the open unit disc is defined by indℳ = dimℳ/zℳ. In this paper, we provide a strong link between high index and nontangential boundary behaviour of the functions in an invariant subspace. Work of the first author was partially supported by the Royal Swedish Academy of Sciences; work of the second and third authors was supported by the National Science Foundation.     

On the exact location of the zeros of certain families of rational period functions and other related rational functions

The classification of Rational Period Functions on the modular group has been of some interest recently, and was accomplished by studying the pole sets of these rational functions. We take a complex analytic point of view and begin an investigation into the location of zeros of certain families of rational period functions.

     

Some applications of the condensation of the singularities of families of nonnegative functions

RecentlyPrus-Wi?niowski [14] has proved that the continuous functions of Λ-bounded variation on [0, 1] form a set of the first category in the Banach space C[0, 1] and also in each Banach space CΓBV[0, 1] of continuous functions of Γ-bounded variation on [0, 1] provided that the sequence Γ is adequate. In the present paper these results are extended and completed by using a principle of the condensation of the singularities of a family of nonnegative functions that follows from the theorems given byBreckner [3]. It is shown that Baire category properties similar to those stated in [14] are valid for two very large classes of real-valued functions called functions of bounded λ-variation of orderp and functions of boundedmth variation of orderp, respectively. The benefit of considering these classes is that they comprise several classes of functions of bounded variation type which have occurred so far in Fourier analysis or real analysis; in particular, the functions investigated in [14]. Thus, by specializing the results derived in the present paper, they give at once Baire category information concerning a number of well-known sets of real-valued functions.