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1.
《数学的实践与认识》2015,(20)
绝对值函数是一个非光滑函数,研究了绝对值函数的光滑逼近函数.给出了绝对值函数的上方一致光滑逼近函数和下方一致光滑逼近函数,分别研究了其性质,并通过图像展示了逼近效果. 相似文献
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利用Nevanlinna理论与多项式加权和的概念研究了一类亚纯函数多项式与其导函数分担小函数的唯一性.在分担小函数的条件下,得到了亚纯函数的特征函数与计数函数之间的一个不等式,并研究了亚纯函数多项式与其k阶导数分担小函数的唯一性问题,所得到的定理补充,改进与推广了一些已有的结果. 相似文献
3.
一类整函数的亏函数 总被引:1,自引:0,他引:1
李庆忠 《纯粹数学与应用数学》1991,7(2):13-16
1964年,庄圻泰教授在整函数的情况彻底解决了R.Nevanlinna提出的关于第二基本定理的推广问题,从而为亏函数的研究开创了道路。在文[2]中,我们用庄圻泰引进的Wronskin行列式作为工具解决了F.Nevanlinna猜想的广泛形式。本文继续用这一工具从推广文[3]中定理2出发,继而给出了一类整函数的亏函数个数。最后对庄圻泰提出的一个问题给出了肯定的回答。 相似文献
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将分段函数划分为连结型分段函数,分离型分段函数和它们的组合形式三种类型,得到了分离型分段函数是初池数的充分必要条件,完整地解决了分离型分段函数与初等函数之间的关系,并且给出了初等函数在其行一截取集上的限制函数(截取函数)仍然是初等函数的结果。 相似文献
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考虑Simon反谱理论新方法中引入的A-函数,根据Weyl函数m关于A-函数的表示关系,利用广义函数和Fourier变换的方法求出A-函数关于Weyl函数m的反表示,该结论表明A-函数的本质是广义函数. 相似文献
6.
讨论了代数体函数的导函数,并首次证明了它也是代数体函数,证明了有限级整代数体函数的级等于其导函数级. 相似文献
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所谓抽象函数就是未给出具体解析式的函数,由于其表达形式的抽象和性质的隐含不露,使得直接求解的思路常难以寻求,再加上还要用到赋值法和配凑技巧,使同学们对抽象函数问题比较害怕,其实,大量的抽象函数都是以中学阶段所学的基本函数为背景抽象而成的,我们称这类基本函数为背景函数,解题时若能根据题设条件,通过类比、联想,猜想出它可能为某种基本函数,然后从这一抽象函数的背景函数入手,就能变抽象为具体,从而会使你的解题思路自然而来。 相似文献
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1.本单元知识点函数是描述客观世界变化规律的重要数学模型.函数内涵丰富、思想深刻、应用广泛,是高中数学的核心知识与关键内容.基本初等函数尽管简单,但非常根本,也能大致满足描摹现实世界的需要.本单元学习重点包括:函数的概念及表示,函数的定义域与值域,函数的单调性与最值、函数的奇偶性,幂运算与对数运算,指数函数、对数函数与幂函数的概念和性质,函数零点与方程根的联 相似文献
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We prove that the Nevanlinna five-point-theorem on the uniqueness of meromorphic functions is valid for five small meromorphic functions. 相似文献
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Constructions and equivalence of APN functions play a significant role in the research of cryptographic functions. On finite fields of characteristic 2, 6 families of power APN functions and 14 families of polynomial APN functions have been constructed in the literature. However, the study on the equivalence among the aforementioned APN functions is rather limited to the equivalence in the power APN functions. Meanwhile, the theoretical analysis on the equivalence between the polynomial APN functions and the power APN functions, as well as the equivalence in the polynomial APN functions themselves, is far less studied. In this paper, we give the theoretical analysis on the inequivalence in 8 known families of polynomial APN functions and power APN functions. 相似文献
13.
The question if there exist nonnormal bent functions was an open question for several years. A Boolean function in n variables is called normal if there exists an affine subspace of dimension n/2 on which the function is constant. In this paper we give the first nonnormal bent function and even an example for a nonweakly normal bent function. These examples belong to a class of bent functions found in [J.F. Dillon, H. Dobbertin, New cyclic difference sets with Singer parameters, in: Finite Fields and Applications, to appear], namely the Kasami functions. We furthermore give a construction which extends these examples to higher dimensions. Additionally, we present a very efficient algorithm that was used to verify the nonnormality of these functions. 相似文献
14.
Yulia Kempner 《Discrete Mathematics》2010,310(22):3211-3218
A function F defined on the family of all subsets of a finite ground set E is quasi-concave, if F(X∪Y)≥min{F(X),F(Y)} for all X,Y⊆E. Quasi-concave functions arise in many fields of mathematics and computer science such as social choice, graph theory, data mining, clustering and other fields. The maximization of a quasi-concave function takes, in general, exponential time. However, if a quasi-concave function is defined by an associated monotone linkage function, then it can be optimized by a greedy type algorithm in polynomial time. Recently, quasi-concave functions defined as minimum values of monotone linkage functions were considered on antimatroids, where the correspondence between quasi-concave and bottleneck functions was shown Kempner and Levit (2003) [6]. The goal of this paper is to analyze quasi-concave functions on different families of sets and to investigate their relationships with monotone linkage functions. 相似文献
15.
A Dirichlet problem for polyharmonic functions 总被引:1,自引:0,他引:1
In this article, the Dirichlet problem of polyharmonic functions is considered. As well the explicit expression of the unique
solution to the simple Dirichlet problem for polyharmonic functions is obtained by using the decomposition of polyharmonic
functions and turning the problem into an equivalent Riemann boundary value problem for polyanalytic functions, as the approach
to find the kernel functions of the solution for the general Dirichlet problem is given.
Project supported by NNSF of China. 相似文献
16.
New classes of generalized Nevanlinna functions, which under multiplication with an arbitrary fixed symmetric rational function remain generalized Nevanlinna functions, are introduced. Characterizations for these classes of functions are established by connecting the canonical factorizations of the product function and the original generalized Nevanlinna function in a constructive manner. Also, a detailed functional analytic treatment of these classes of functions is carried out by investigating the connection between the realizations of the product function and the original function. The operator theoretic treatment of these realizations is based on the notions of rigged spaces, boundary triplets, and associated Weyl functions. 相似文献
17.
Feng Qi Run-Qing Cui Bai-Ni Guo 《Journal of Mathematical Analysis and Applications》2005,310(1):303-308
By using the first Binet's formula the strictly completely monotonic properties of functions involving the psi and polygamma functions are obtained. As direct consequences, two inequalities are proved. As an application, the best lower and upper bounds of the nth harmonic number are established. 相似文献
18.
The problem of extending partial functions is considered from the general viewpoint. Some aspects of this problem are illustrated by examples, which are concerned with typical real-valued partial functions (e.g. semicontinuous, monotone, additive, measurable, possessing the Baire property). 相似文献
19.
In this paper, we will prove some uniqueness theorems of meromorphic functions whose derivatives share four distinct small functions. The results in this paper improve those given by R. Nevanlinna, L. Yang, G.D. Qiu, and other authors. An example is provided to show that the results in this paper are best possible. 相似文献
20.
Yulia Kempner 《Discrete Applied Mathematics》2008,156(4):492-499
This paper deals with maximization of set functions defined as minimum values of monotone linkage functions. In previous research, it has been shown that such a set function can be maximized by a greedy type algorithm over a family of all subsets of a finite set. In this paper, we extend this finding to meet-semilattices.We show that the class of functions defined as minimum values of monotone linkage functions coincides with the class of quasi-concave set functions. Quasi-concave functions determine a chain of upper level sets each of which is a meet-semilattice. This structure allows development of a polynomial algorithm that finds a minimal set on which the value of a quasi-concave function is maximum. One of the critical steps of this algorithm is a set closure. Some examples of closure computation, in particular, a closure operator for convex geometries, are considered. 相似文献