时滞系统的鲁棒性与边界定理

本文首先注意到滞后型拟多项式与中立型拟多项式零点分布的根本区别，并指出一些通常的事实：如特征根对时滞的连续依赖性，所有特征根位于开左半复平面与稳定性的等价关系等对于中立型系统都不成立，然后建立了中立型拟多项式胞鲁棒稳定性的边界定理．依此将可公度时滞中立型系统族的鲁棒稳定性化为相应拟多项式胞所有边的Ｈｕｒｗｉｔｚ稳定性与其中立型项构成的子胞所有边的Ｓｃｈｕｒ稳定性的判定．最后给出了检验中立型胞鲁棒稳定性的一个有效的图解法．     

An algebraic approach to q-partial fractions and Sylvester denumerants

The Ramanujan Journal - In 1857, Sylvester established an elegant theory that certain counting functions (which he termed denumerants) are quasi-polynomials by decomposing them into periodic and...     

Necessary stability conditions for differential-difference equations

Hurwitz-stable polynomials and quasi-polynomials are split to construct positive rational functions. Computational characterizations of positive functions are used to derive low-order necessary stability criteria. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dimension polynomials of difference local algebras

We extend the concept of the difference dimension polynomial of a difference field extension to difference local algebras. The main theorem of the paper establishes the existence and form of the dimension polynomial associated with the localization of a finitely generated well-mixed difference algebra at a prime reflexive difference ideal.     

Fourth-order difference equation for the associated Meixner and Charlier polynomials

An explicit representation of the associated Meixner polynomials (with a real association parameter γ?0) is given in terms of hypergeometric functions. This representation allows to derive the fourth-order difference equation verified by these polynomials. Appropriate limits give the fourth-order difference equation for the associated Charlier polynomials and the fourth-order differential equations for the associated Laguerre and Hermite polynomials.     

Maximal periods of (Ehrhart) quasi-polynomials

A quasi-polynomial is a function defined of the form q(k)=cd(k)kd+cd−1(k)kd−1+?+c₀(k), where c₀,c₁,…,cd are periodic functions in k∈Z. Prominent examples of quasi-polynomials appear in Ehrhart's theory as integer-point counting functions for rational polytopes, and McMullen gives upper bounds for the periods of the cj(k) for Ehrhart quasi-polynomials. For generic polytopes, McMullen's bounds seem to be sharp, but sometimes smaller periods exist. We prove that the second leading coefficient of an Ehrhart quasi-polynomial always has maximal expected period and present a general theorem that yields maximal periods for the coefficients of certain quasi-polynomials. We present a construction for (Ehrhart) quasi-polynomials that exhibit maximal period behavior and use it to answer a question of Zaslavsky on convolutions of quasi-polynomials.     

A problem about the difference of functions with equidistant knots

The asymptotic properties of mean value in the relationship between difference and derivatives of functions in case of equidistance knots are discussed.     

On the Loewy Length and the Noetherian Dimension of Artinian Modules

The problem of computing the automorphism groups of an elementary Abelian Hadamard difference set or equivalently of a bent function seems to have attracted not much interest so far. We describe some series of such sets and compute their automorphism group. For some of these sets the construction is based on the nonvanishing of the degree 1-cohomology of certain Chevalley groups in characteristic two. We also classify bent functions f such that Aut(f) together with the translations from the underlying vector space induce a rank 3 group of automorphisms of the associated symmetric design. Finally, we discuss computational aspects associated with such questions.     

Large Toeplitz Systems with Quasi-polynomial Right-hand Sides

We consider the asymptotics of the solutions of large linear systems with Toeplitz matrices generated by a complex valued symbol which is infinitely differentiable, has no zeros on the unit circle, and whose winding number about the origin is zero. The emphasis is on quasi-polynomials as right-hand sides, in which case we show that the central fragment of the solution is asymptotically also a quasi-polynomial. Moreover, we establish asymptotic formulas that give specific components of the solution independently of the other components. We are greatly indebted to the referees for suggesting substantial simplifications in our original proofs and the constructive advice which helped to improve the exposition.     

Uniqueness and value distribution of differences of entire functions

We consider the existence of transcendental entire solutions of certain type of non-linear difference equations. As an application, we investigate the value distribution of difference polynomials of entire functions. In particular, we are interested in the existence of zeros of fn(z)(λfm(z+c)+μfm(z))−a, where f is an entire function, n, m are two integers such that n?m>0, and λ, μ are non-zero complex numbers. We also obtain a uniqueness result in the case where shifts of two entire functions share a small function.     

Mochizuki's indigenous bundles and Ehrhart polynomials

Mochizuki's work on torally indigenous bundles [1] yields combinatorial identities by degenerating to different curves of the same genus. We rephrase these identities in combinatorial language and strengthen them, giving relations between Ehrhart quasi-polynomials of different polytopes. We then apply the theory of Ehrhart quasi-polynomials to conclude that the number of dormant torally indigenous bundles on a general curve of a given type is expressed as a polynomial in the characteristic of the base field. In particular, we conclude the same for the number vector bundles of rank two and trivial determinant whose Frobenius-pullbacks are maximally unstable, as well as self-maps of the projective line with prescribed ramification. The second author was supported by a fellowship from the Japan Society for the Promotion of Science during the preparation of this paper.     

On properties of difference polynomials

We study the value distribution of difference polynomials of meromorphic functions, and extend classical theorems of Tumura-Clunie type to difference polynomials. We also consider the value distribution of f (z)f (z + c).     

Backward Euler Scheme,Singular Hölder Norms,and Maximal Regularity for Parabolic Difference Equations

We show finite difference analogues of maximal regularity results for discretizations of abstract linear parabolic problems. The involved spaces are discrete versions of spaces of Hölder continuous functions, which can be singular in 0. The main tools are real interpolation and Da Prato–Grisvard's theory of the sum of linear operators.     

拟二次多项式的迭代

本文初次探讨了更广泛的拟多项式迭代．得到几个初步的定理．希望将复动力系统的一些定理推广到拟动力系统．     

Recursive formulation of the relativistic law of superposition of multiple collinear velocities

We study the recursive formulation of the law of superposition of multiple collinear velocities. We start with the non-linear equation, transform it into two linear coupled difference equations with variable cofficients, and then decouple these latter equations. The coupled difference equations are solved by three different, but interrelated, methods: (i) via the graph theoretic discrete path approach, (ii) by using the general closed form solution of two coupled first order difference equations with variable coefficients, and (iii) in terms of the symmetric functions via the pochhammers of 2 × 2 non-autonomous matrices. The solutions of the decoupled equations are factorial polynomials.     

Discrete kiguradze type inequalities

Solutions of nth order difference inequalities satisfying n boundary conditions of predetermined sign are compared to solutions of difference equalities satisfying n?1 homogenous boundary conditions. The inequalities obtained here apply to Green's functions of corresponding boundary value problems     

Recurrence relations for discrete hypergeometric functions

We present a general procedure for finding linear recurrence relations for the solutions of the second order difference equation of hypergeometric type. Applications to wave functions of certain discrete system are also given.     

Remarks on the Notion of Order of Difference Equations

In the paper, the notion of order of a difference equation is introduced in such a way that this order is invariant with respect to the change of the independent variable. For the general case, a formula for the general solution of linear difference equation of k -th order is given. It is shown that, in contrast to differential equations, the dimension of the linear space of solutions of linear homogenous difference equation can be lowered if their domain of definition is restricted appropriately.     

Multiple-scale analysis of dynamical systems on the lattice

We propose a new approach to the multiple-scale analysis of difference equations, in the context of the finite operator calculus. We derive the transformation formulae that map any given dynamical system, continuous or discrete, into a rescaled discrete system, by generalizing a classical result due to Jordan. Under suitable analytical hypotheses on the function space we consider, the rescaled equations are of finite order. Our results are applied to the study of multiple-scale reductions of dynamical systems, and in particular to the case of a discrete nonlinear harmonic oscillator.