A Hartman-Grobman result for retarded functional differential equations with an application to the numerics around hyperbolic equilibria

A weak form of the Hartman-Grobman theorem for retarded functional differential equations around hyperbolic equilibria is presented. Orbits on a center-unstable manifold are compared to orbits on a center-unstable subspace of the linearized equation. The result is applied to obtain a conjugacy between the semidynamical system generated by the functional differential equation and its numerical approximation. A version of the Hartman-Grobman theorem around hyperbolic periodic orbits of functional differential equations is also given.     

Construction of differential equation approximations to delay differential equations

A constructive method is presented for obtaining differential equation approximations to general functional delay differential equations. It is shown that the approximating differential equation systems can be used to determine the stability of the functional differential equations     

Lipschitzian semigroups and abstract functional differential equations

The paper is devoted to studying an abstract functional differential equation by a nonlinear semigroup approach. We first prove in details the equivalence of the well posedness of an abstract functional differential equation and an associated abstract Cauchy problem in the sense of strong solutions. Secondly, a sufficient condition is derived for well posedness of the abstract functional differential equation. Thirdly, we present principles of linearized stability for the abstract functional differential equation. Finally, the results obtained are applied to a reaction-diffusion equation with delays.     

高阶中立型泛函微分方程的周期解

运用迭合度理论和分析的技巧,研究一类具分布时滞的中立型高阶泛函微分方程,并得到了其周期解存在的充分条件。     

Global Attractivity of Nonautonomous Inshore-Offshore Fishing Models with Stage-structure

The article deals with a nonautonomous fishing model with stage-structure in inshore and offshore. By using the theory of monotone of functional differential equation and the concave operator theory of functional differential equation, the stability of the positive periodic solution of a dynamical system representing the fishery are derived, and their globally attracting behaviour is discussed. A briefly biology meaning of the mathematical results is given.     

Functional differential inequalities and estimation of the Cauchy function of an equation with aftereffect

We consider scalar functional differential inequalities that are used to estimate solutions to differential equations with deviating argument. A theorem on positiveness of the Cauchy function of a differential equation with aftereffect is derived from a theorem on a functional differential inequality with nonlinearmonotone operator, which is a direct generalization of the simplest classical theorem on a differential inequality. The suggested proofs rely on local properties of continuous functions only.     

A neutral FDE with stable D-operator is retarded

A neutral functional differential equation with a linear, autonomous, and stable D-operator can be rewritten as a retarded functional differential equation with infinite delay. This fact can be used, e.g., in the study of the stability of the neutral equation and to simplify the proofs of some standard asymptotic results.     

Periodic solutions of retarded functional differential equations

The classical criterion for the existence of a periodic solution of a forced, linear, retarded functional differential equation (rfde) references the solution of an adjoint equation which is an advanced functional differential equation. This paper introduces a new criterion which does away with the (anti-causal) advanced functional differential equation.     

The method of noncommutative integration for linear differential equations. Functional algebras and noncommutative dimensional reduction

The method of noncommutative integration for linear partial differential equations [1] is extended to the case of the so-called functional algebras for which the commutators of their generators are nonlinear functions of the same generators. The linear functions correspond to Lie algebras, whereas the quadratics are associated with the so-called quadratic algebras having wide applications in quantum field theory. A nontrivial example of integration of the Klein-Gordon equation in a curved space not allowing separation of variables is considered. A classification of four- and five-dimensional quadratic algebras is performed.A method of dimensional reduction for noncommutatively integrable many-dimensional partial differential equations is suggested. Generally, the reduced equation has a complicated functional symmetry algebra. The method permits integration of the reduced equation without the use of the explicit form of its functional algebra.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 106, No. 1, pp. 3–15, January, 1996.     

Differential games with a given value function

The set of solutions of a differential game with a terminal payoff functional is investigated. A method is obtained that allows us to establish whether a given function is a value of some differential game with a terminal payoff functional. The condition obtained is in fact the condition for the given function to be a minimax (viscosity) solution of some Hamilton-Jacobi equation with Hamiltonian homogeneous in the third variable. We also obtain a sufficient condition for a function to belong to the set of values of differential games with a terminal payoff function.     

Optimal control problems for wave equations

The problem on minimizing a quadratic functional on trajectories of the wave equation is considered. We assume that the density of external forces is a control function. A control problem for a partial differential equation is reduced to a control problem for a countable system of ordinary differential equations by use of the Fourier method. The controllability problem for this countable system is considered. Conditions of the noncontrollability for some wave equations were obtained.     

Coleman integration using the Tannakian formalism

We use a new idea to construct a theory of iterated Coleman functions on overconvergent spaces with good reduction in any dimension. A Coleman function in this theory consists of a unipotent differential equation, a functional on the underlying bundle and a solution to the equation on a residue class. The new idea is to use the theory of Tannakian categories and the action of Frobenius to analytically continue solutions of the differential equation to all residue classes. Received: 22 November 2000 / Revised version: 28 March 2001 / Published online: 24 September 2001     

Asymptotic behavior and oscillation of functional differential equations

Asymptotic relations between the solutions of a linear autonomous functional differential equation and the solutions of the corresponding perturbed equation are established. In the scalar case, it is shown that the existence of a nonoscillatory solution of the perturbed equation often implies the existence of a real eigenvalue of the limiting equation. The proofs are based on a recent Perron type theorem for functional differential equations.     

一类二阶非线性泛函微分方程的振动性

讨论了一类二阶非线性泛函微分方程的振动性,得到了该类方程所有解振动的新的充分条件,改进并推广了已有的结果.     

具连续分布滞量的二阶中立型方程的振动性定理

利用直接分析方法研究一类具有连续分布滞量的二阶非线性中立型方程解的性质，获得了类具连续分布滞量的二阶非线性中立型泛函微分方程所有解振动的若干充分条件．     

Asymptotic Analysis for a Class of Infinite Systems of First-Order PDE: Nonlinear Parabolic PDE in the Singular Limit

Abstract

We study the asymptotic behavior of solutions of the Cauchy problem for a functional partial differential equation with a small parameter as the parameter tends to zero. We establish a convergence theorem in which the limit problem is identified with the Cauchy problem for a nonlinear parabolic partial differential equation. We also present comparison and existence results for the Cauchy problem for the functional partial differential equation and the limit problem.     

Oscillation of partial population model with diffusion and delay

By using the upper- and lower-solution method of partial functional differential equations and the oscillation theory of functional differential equation, the oscillation of a population equation with diffusion and delay is studied and a sufficient condition for all positive solutions of the equation to oscillate about the positive equilibrium is obtained. Finally, a model arising from ecology is given to illustrate the obtained results.     

一类二阶非线性泛函微分方程的振动性

考虑一类二阶非线性泛函微分方程,得到了方程的解的导数振动的一个充分条件,推广和改进了Lee和Yeh的相关结论.     

Error Estimates for a Class of Elliptic Optimal Control Problems

In this article, functional type a posteriori error estimates are presented for a certain class of optimal control problems with elliptic partial differential equation constraints. It is assumed that in the cost functional the state is measured in terms of the energy norm generated by the state equation. The functional a posteriori error estimates developed by Repin in the late 1990s are applied to estimate the cost function value from both sides without requiring the exact solution of the state equation. Moreover, a lower bound for the minimal cost functional value is derived. A meaningful error quantity coinciding with the gap between the cost functional values of an arbitrary admissible control and the optimal control is introduced. This error quantity can be estimated from both sides using the estimates for the cost functional value. The theoretical results are confirmed by numerical tests.     

On Reducible Linear Functional Differential Equations of Mixed Type

There are occasions when a linear autonomous functional differential equation of mixed type can be reduced to a neutral or retarded equation. A necessary condition for such reducibility is shown to be that the set of solutions of the characteristic equation is bounded on the right in the complex plane. This condition is also suffcient for the reducibility of a class of mixed‐type equations.