On the Hyper-Order of Solutions of Some Second-Order Linear Differential Equations

In this paper, we investigate the growth of solutions of the second-order linear homogeneous differential equations with entire coefficients of the same order, and obtain precise estimates of the hyper-order of their solutions. Received November 15, 1999, Accepted May 10, 2000     

二阶线性微分方程亚纯解的不动点与超级

本文研究了以亚纯函数为系数的二阶线性微分方程的解及其一阶和二阶导数的不动点及超级问题，得到：二阶线性微分方程亚纯解及其一阶和二阶导数的不动点性质，由于受到微分方程的限制，与一般亚纯函数的不动点性质相比是十分有趣的，事实上，它们与解的增长性密切相关。     

Differential polynomials generated by linear differential equations

This article is devoted to considering value distribution theory of differential polynomials generated by solutions of linear differential equations in the complex plane. In particular, we consider normalized second-order differential equations f″+A(z)f=0, where A(z) is entire. Most of our results are treating the growth of such differential polynomials and the frequency of their fixed points, in the sense of iterated order.     

Constants of Derivation and Differential Ideals

ABSTRACT

Let R be a differential domain finitely generated over a differential field F of characteristic 0. Let C be the subfield of differential constants of F. This paper investigates conditions on differential ideals of R that are necessary or sufficient to guarantee that C is also the set of constants of differentiation of the quotient field, E, of R. In particular, when C is algebraically closed and R has a finite number of height one differential prime ideals, there are no new constants in E. An example where F is infinitely generated over C shows the converse is false. If F is finitely generated over C and R is a polynomial ring over F, sufficient conditions on F are given so that no new constants in E does imply only finitely many height one prime differential ideals in R. In particular, F can be Q¯(T) where T is a finite transcendence set.

     

非齐次线性微分方程解的增长性

研究了非齐次线性微分方程f^{(k)}+A_{k-1}(z)f^{(k-1)}+...+A_{s}(z)f^{(s)}+...+A_{0}(z)f=F(z) 解的增长性,其中A_{j}(j=0,1,\cdots,k-1)及F是整函数. 在A_{s}比其他系数有较快增 长的情况下,得到了上述非齐次微分方程在一定条件下的超越整函数解的超级的精确估计.     

关于高阶整函数系数微分方程解的超级

研究两种类型的高阶线性齐次整函数系数微分方程解的增长性问题。对于这两种类型的方程,当存在某个系数对方程的解的性质起主要支配作用时,得到了方程解的超级的估计,特别是对零点收敛指数是有穷的解,得到了解的超级的精确估计。     

一类高阶整函数系数微分方程解的增长级、下级与超级

该文研究了一类高阶整函数系数微分方程解的增长性,对方程f~(k)+A_(k-1)(z)e~(ak-1z).f~(k-1)+…+A_0(z)e~(a0z)f=0与方程f~(k)+(A_(k-1)(z)e~(ak-1z)+D_(k-1)(z))f~(k-1)+…+(A_0(z)e~(a0z)+D_0(z))f=0中a_j(0≤j≤k-1)幅角主值不全相等的情形,得到了解的增长级、下级与超级的精确估计.     

Differential Inequalities and Starlikeness

We study some differential inequalities in the unit disc which imply starlikeness: for example if ? (z) = z + Σ^∞ _n=2 a_n (?)zⁿ is analytic in D = {z | |z| < 1} and |z(?′′(z) ? 1)| ≤ 1 ? α, z?D for some α ] [0, 1), then ? is one-to-one on D and ? (D) is a starlike domain with respect to the origin.     

On the Growth and Fixed Points of Solutions of Second Order Differential Equations with Meromorphic Coefficients

In this paper, we investigate the growth and fixed points of solutions and their 1st, 2nd derivatives, differential polynomial of second order linear differential equations with meromorphic coefficients, and obtain that the exponents of convergence of these fixed points are all equal to the order of growth.     

Regular Functions Satisfying Irregular Ordinary Differential Equations

This paper deals with entire solutions to linear ordinary differential equations in the complex domain. We show that certain entire solutions to singular equations, cannot satisfy any normalized equation without singularities. We provide two proofs of this result, one based on the indicial equation and the other using the Frobenius notion of irreducibility. Our examples include the entire Bessel function.     

On the Explicit Solution of Certain First Order Systems of Partial Differential Equations

We consider two classes of systems of partial differential equations of first order. One consists of generalized Stokes-Beltrami equations $ Aw_z = w^*_z $ , $ \lambda Bw_{\bar z} -w^*_{\bar z} $ with square matrices A and B and a scalar factor u . The other may be written in matrix notation as $ v_{\bar z} = c{\bar v} $ where c denotes a square matrix. This system is known as a Pascali system. Both systems are in close connections to certain systems of second order for which the solutions can be represented using particular differential operators. On the basis of these relations we give the solutions of the first order systems explicitly.     

Second Order Scalar Functional Differential Equations with Piecewise Constant Arguments

The study of functional differential equations with piecewise constant arguments usually results in a study of certain related difference equations. In this paper we consider certain neutral functional differential equations of this type and the associated difference equations. We give conditions under which such equations with almost periodic time dependence will have unique almost periodic solutions, and for certain autonomous cases, we obtain certain stability results and also conditions for chaotic behavior of solutions. We are particularly concerned with such equations which are partially discretized versions of non-forced Duffing equations.     

Existence of Solution of Nonlinear Neutral Stochastic Differential Inclusions with Infinite Delay

Abstract

This article is concerned with the existence of solution of nonlinear neutral stochastic differential inclusions with infinite delay in a Hilbert Space. Sufficient conditions for the existence are obtained by using a fixed point theorem for condensing maps due to Martelli.     

Importance Sampling,Large Deviations,and Differential Games

A standard heuristic in the area of importance sampling is that the changes of measure used to prove large deviation lower bounds give good performance when used for importance sampling. Recent work, however, has shown that a naive implementation of the heuristic is incorrect in many situations. The present paper considers the simple setting of sums of independent and identically distributed (iid) random variables, and shows that under mild conditions asymptotically optimal changes of measure can be found if one considers dynamic importance sampling schemes. For such schemes, the change of measure applied to an individual summand can depend on the historical empirical mean of the simulation (i.e. the system state). In analyzing the asymptotic performance of importance sampling, we show that the value function of a differential game characterizes the optimal performance, with player A corresponding to the choice of change of measure and player B arising due to a large deviations analysis. From this perspective, the traditional implementation of the heuristic is shown to correspond to player A choosing a control that is fixed, regardless of the system state or player B's choice of control. This leads to an "open loop" control for player A, which is suboptimal except in special cases. Our final contribution is a method, based on the Isaacs equation associated with the differential game, for constructing dynamic schemes. Numerical examples are presented to illustrate the results.     

Oscillatory Periodic Solutions of Nonlinear Second Order Ordinary Differential Equations

In this paper the existence results of oscillatory periodic solutions are obtained for a second order ordinary differential equation -u″（t） = f（t, u（t））, where f ： R^2 → R is a continuous odd function and is 2π-periodic in t. The discussion is based on the fixed point index theory in cones.     

Interpolation by hypercyclic functions for differential operators

We prove that, given a sequence of points in a complex domain Ω without accumulation points, there are functions having prescribed values at the points of the sequence and, simultaneously, having dense orbit in the space of holomorphic functions on Ω. The orbit is taken with respect to any fixed nonscalar differential operator generated by an entire function of subexponential type, thereby extending a recent result about MacLane-hypercyclicity due to Costakis, Vlachou and Niess.     

Backward Stochastic Differential Equation with Two Reflecting Barriers and Jumps

Abstract

In this paper, by using a penalization as well as a fixed point methods, we prove existence and uniqueness of the solution for the one-dimensional reflected backward stochastic differential equation when the noise is driven by a Brownian motion and an independent Poisson point process.     

Holomorphic Differential Operators and Plane Sets with Dense Images

We prove in this paper that, given a nonempty open set G in the complex plane, a subset A of G which is not relatively compact and a holomorphic infinite order differential or antidiffeärential operator T, then there are holomorphic functions ? on G such that the image of A under T ? is dense in the complex plane. This extends a recent result about a property of boundary behaviour exhibited by the derivative operator.     

Surjectivity and fixed points of relaxed dissipative multifunctions. Differential inclusions approach

One from the most important properties of accretive and monotone operators is the existence of zeros and surjectivity. In the paper we introduce relaxed variants of dissipative, accretive and monotone operators. Using essentially the properties of the solution set of appropriate differential inclusions we study the existence of zeros of such operators. As corollaries the existence of fixed points of relaxed contractive and relaxed nonexpansive multifunctions are obtained.     

Impulsive Boundary Value Problems for First-order Ordinary Differential Inclusions

In this paper, we investigate the existence of solutions for impulsive first order ordinary differential inclusions which admitting nonconvex valued right hand side. We present two classes of results. In the first one, we rely on a fixed point theorem for contraction multivalued maps due to Covitz and Nadler, and for the second one, we use Schacfer＇s fixed point theorem combined with lower semi-continuous multivalued operators with decomposable values under weaker conditions.