具有可变时滞的非线性非自治差分方程的振动性及其应用

本文获得了一类具有可变时滞的非线性非自治差分方程的振动准则,建立了这类差分方程的几个线性化振动性定理,并得到了具有可变时滞的离散型非自治广义Logistic方程关于其正平衡点振动的一系列充分条件.     

OSCILLATION THEOREMS FOR SECOND ORDER NEUTRAL DIFFERENCE EQUATIONS

The aim of this paper is to study the oscillation of second order neutral difference equations.Our results are based on the new comparison theorems,that reduce the problem of the oscillation of the second order equation to that of the first order equation.The comparison principles obtained essentially simplify the examination of the equations.     

Oscillation criteria for certain even order quasilinear difference equations

Some new oscillation theorems for even-order difference equations of the form $$\Delta(|\Delta^{k-1}x_{n}|^{\alpha-1}\Delta ^{k-1}x_{n})+f(n,x_{\sigma(n)})=0$$ are obtained. Our results generalize some well-known results for second order difference equations.     

Oscillation of second-order nonlinear delay dynamic equations with damping on time scales

By using the generalized Riccati transformation and the inequality technique, we establish some new oscillation criteria for the second-order nonlinear delay dynamic equations with damping on a time scale. Our results extend and improve some known theorems, but also unify the oscillation of the second-order nonlinear delay differential equation with damping and the second-order nonlinear delay difference equation with damping.     

Connection between spectral and oscillation properties of differential-operator equations of arbitrary order. II. Applications of factorization and squaring

Factorization theorems of Frobenius and M. G. Krein-Heinz-Rellich type are established for infinite systems of differential equations of arbitrary even order on finite or infinite intervals. From here, Etgen and Pawlowski oscillation theorems, referring to second order equations, are generalized to the considered equations of order 2n and also a variant of a Sturm type comparison theorem is derived. An analogue of the oscillation theorem for discrete levels in the gap of the continuous spectrum is obtained for problems of both even and odd order.Translated from Teoriya Funktsii, Funktsional'nyi Analiz i Ikh Prilozheniya, No. 49, pp. 101–111, 1988.     

Property (A) of third-order advanced differential equations

In the paper we offer criteria for property (A) of the third-order nonlinear functional differential equation with advanced argument $(a(t)(x'(t))^\gamma )'' + p(t)f(x(\sigma (t))) = 0,$ , where $\mathop \smallint \limits^\infty a^{ - 1/\gamma } (s)ds = \infty $ . We establish new comparison theorems for deducing property (A) of advanced differential equations from that of ordinary differential equations without deviating argument. The presented comparison principle fill the gap in the oscillation theory.     

Calculation of solutions to the Mathieu equation and of related quantities

For the Mathieu equation, we consider finding eigenvalues with a given index (on the basis of oscillation theorems for the relevant difference equations), the stability of solutions to the difference equations, correct definition and calculation of eigenvalues and Mathieu functions with noninteger numbers, correct definition and calculation of the Mathieu characteristic exponent, and the calculation of values of solutions to the Mathieu equation for large arguments. Numerical algorithms are proposed for the problems listed above.     

Oscillation and nonoscillation of solutions of second order linear dynamic equations with integrable coefficients on time scales

We obtain Willett-Wong-type oscillation and nonoscillation theorems for second order linear dynamic equations with integrable coefficients on a time scale. The results obtained extend and are motivated by oscillation and nonoscillation results due to Willett [20] and Wong [21] for the second order linear differential equation. As applications of the new results obtained, we give the complete classification of oscillation and nonoscillation for the difference equations

     

COMPERISON THEOREMS AND SUFFICIENT AND NECESSARY CONDITION FOR OSCILLATION OF FIRST ORDER NEUTRAL NONLINEAR DIFFERENTIAL EQUATIONS

ＣＯＭＰＥＲＩＳＯＮＴＨＥＯＲＥＭＳＡＮＤＳＵＦＦＩＣＩＥＮＴＡＮＤＮＥＣＥＳＳＡＲＹＣＯＮＤＩＴＩＯＮＦＯＲＯＳＣＩＬＬＡＴＩＯＮＯＦＦＩＲＳＴＯＲＤＥＲ　ＮＥＵＴＲＡＬＮＯＮＬＩＮＥＡＲＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＬｉＷａｎｔｏｎｇ...     

Picone type formula for half‐linear impulsive differential equations with discontinuous solutions

Picone type formula for half‐linear impulsive differential equations with discontinuous solutions having fixed moments of impulse actions is derived. Employing the formula, Leighton and Sturm–Picone type comparison theorems as well as several oscillation criteria for impulsive differential equations are obtained. Copyright © 2014 John Wiley & Sons, Ltd.     

Oscillation criteria of second order neutral difference equations

Some Riccati type difference inequalities are established for the second-order nonlinear difference equations with negative neutral term $$\Delta (a(n)\Delta (x(n) - px(n - \tau ))) + f(n,x(\sigma (n))) = 0$$ using these inequalities we obtain some oscillation criteria for the above equation.     

On the oscillation properties of first-order impulsive differential equations with a deviating argument

For first order linear impulsive differential equations with a deviating argument a number of oscillation theorems are proved (of the type of the Sturmian Theorem). Various criteria for oscillation or non-oscillation of the solutions of these equations are found. The oscillatory properties of some concrete equations of the type considered are investigated. Supported by the Bulgarian Ministry of Education, Science and Technologies under Grant MM-422.     

Oscillation Theorems for a Nonlinear System of Differential Equations

We shall establish some theorems analogous to Kneser's oscillation theorems for the linear differential equation of second order, which give sufficient conditions for oscillation of all solutions of the system of differential equations of the type u′i = |u3-i|λi sgn u3-i + (-1)i-1bi(t)ui (i = 1,2), where the functions bi (i = 1, 2) are nonnegative and summable on each finite segment of the interval [0, + ∞) and λi > 0 (i = 1, 2).     

Comparison theorems for oscillation of second-order half-linear differential equations

Summary We establish new comparison theorems on the oscillation of solutions of a class of perturbed half-linear differential equations. These improve the work of Elbert and Schneider [6] in which connections are found between half-linear differential equations and linear differential equations. Our comparison theorems are not of Sturm type or Hille--Wintner type which are very famous. We can apply the main results in combination with Sturm's or Hille--Wintner's comparison theorem to a half-linear differential equation of the general form (|x'|^α-1x')' + a(t) |x|^α-1x = 0.     

Estimates for the solutions of systems of linear algebraic equations and their application to the investigation of the convergence of the method of finite differences

One proves theorems regarding the estimates of the solutions of systems of linear algebraic equations and inequalities. On the basis of these theorems one suggests a method for estimating the norm of the inverse matrix of a system of difference equations which approximates a boundary-value problem for an integrodifferential equation. The method allows us to eliminate the restrictions which are usually imposed on the coefficients of the integrodifferential equation in order to ensure the diagonal dominance in the system of the difference equations. One considers an application to nonlinear problems.     

Oscillation criteria for second-order nonlinear differential equations with damping

For a second-order nonlinear differential equation with a damping term, we obtain new oscillation criteria without an assumption that has been required for related results reported in the literature over the last two decades. Two approaches refining the standard integral averaging technique suggested in the paper can be used to derive a variety of simpler oscillation theorems for different classes of nonlinear differential equations, and both sets of oscillation criteria established in the paper are of independent interest. Several examples are provided to illustrate the relevance of the new theorems.     

Nonlinear oscillations of fourth order quasilinear ordinary differential equations

We consider fourth order quasilinear ordinary differential equations. Firstly, we classify positive solutions into four types according to their asymptotic properties. Then we derive existence theorems of positive solutions belonging to each type. Using these results, we can obtain an oscillation criterion, which is our main objective. Moreover, applying such criteria for ordinary differential equations to binary elliptic systems, we establish nonexistence theorems for positive solutions.     

Estimates of the solutions of two-point boundary-value problems for systems of first-order integrodifferential equations and the method of lines

One proves theorems on the estimates of the solutions of the systems of first-order integrodifferential equations with the boundary conditions On the basis of these theorems, one suggests a method for estimating the norms of integrodifferential equations by the method of the lines for the solutions of the periodic boundary-value problems for second-order integrodifferential equations of parabolic type. On the basis of the established theorem, on the solvability and on the estimate of the solution of the nonlinear equation $$Tx + F\left( x \right) = 0$$ in a Banach space X, where T is a linear unbounded operator, one investigates the convergence of the method of lines for solving the periodic boundary-value problem for a second-order nonlinear integrodifferential equation of parabolic type.     

Nonoscillation theorems of second order nonlinear differential equations

The main purpose of this paper is to study the existence of nonoscillatory solutions of the second order non-linear differential equation (1). The author first generalizes a Wintner's lemma [1,8] to nonlinear equations (i.e. the following Theorem 1 and 4), and then obtains the necessary and sufficient conditions for the existence of nonoscillatory solutions of (1). These theorems generalize the corresponding results of [1] to include nonlinear equations. Using the above results, the author further obtains a series of criterion theorems for the existence of nonoscillatory solutions and comparison theorems for the oscillation and nonoscillation of nonlinear equations.