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A criterion for convergence of solutions of homogeneous delay linear differential equations

Josef Diblík (1999)

Annales Polonici Mathematici

The linear homogeneous differential equation with variable delays ( t ) = j = 1 n α j ( t ) [ y ( t ) - y ( t - τ j ( t ) ) ] is considered, where α j C ( I , ͞ ͞ ) , I = [t₀,∞), ℝ⁺ = (0,∞), j = 1 n α j ( t ) > 0 on I, τ j C ( I , ) , the functions t - τ j ( t ) , j=1,...,n, are increasing and the delays τ j are bounded. A criterion and some sufficient conditions for convergence of all solutions of this equation are proved. The related problem of nonconvergence is also discussed. Some comparisons to known results are given.

A Perron-type theorem for nonautonomous delay equations

Luis Barreira, Claudia Valls (2013)

Open Mathematics

We show that if the Lyapunov exponents of a linear delay equation x′ = L(t)x t are limits, then the same happens with the exponential growth rates of the solutions to the equation x′ = L(t)x t + f(t, x t) for any sufficiently small perturbation f.

A remark on second order functional-differential systems

Valter Šeda, Štefan Belohorec (1993)

Archivum Mathematicum

It is proved that under some conditions the set of solutions to initial value problem for second order functional differential system on an unbounded interval is a compact R δ -set and hence nonvoid, compact and connected set in a Fréchet space. The proof is based on a Kubáček’s theorem.

An asymptotic theorem for a class of nonlinear neutral differential equations

Manabu Naito (1998)

Czechoslovak Mathematical Journal

The neutral differential equation (1.1) d n d t n [ x ( t ) + x ( t - τ ) ] + σ F ( t , x ( g ( t ) ) ) = 0 , is considered under the following conditions: n 2 , τ > 0 , σ = ± 1 , F ( t , u ) is nonnegative on [ t 0 , ) × ( 0 , ) and is nondecreasing in u ( 0 , ) , and lim g ( t ) = as t . It is shown that equation (1.1) has a solution x ( t ) such that (1.2) lim t x ( t ) t k exists and is a positive finite value if and only if t 0 t n - k - 1 F ( t , c [ g ( t ) ] k ) d t < for some c > 0 . Here, k is an integer with 0 k n - 1 . To prove the existence of a solution x ( t ) satisfying (1.2), the Schauder-Tychonoff fixed point theorem is used.

Analysis of a Nonautonomous HIV/AIDS Model

G. P. Samanta (2010)

Mathematical Modelling of Natural Phenomena

In this paper we have considered a nonlinear and nonautonomous stage-structured HIV/AIDS epidemic model with an imperfect HIV vaccine, varying total population size and distributed time delay to become infectious due to intracellular delay between initial infection of a cell by HIV and the release of new virions. Here, we have established some sufficient conditions on the permanence and extinction of the disease by using inequality analytical technique....

Approximate properties of principal solutions of Volterra-type integrodifferential equations with infinite aftereffect

Yu. A. Ryabov (1995)

Mathematica Bohemica

The integrodifferential system with aftereffect (“heredity” or “prehistory”) dx/dt=Ax+-t R(t,s)x(s,)ds, is considered; here ε is a positive small parameter, A is a constant n × n matrix, R ( t , s ) is the kernel of this system exponentially decreasing in norm as t . It is proved, if matrix A and kernel R ( t , s ) satisfy some restrictions and ε does not exceed some bound ε * , then the n -dimensional set of the so-called principal two-sided solutions x ˜ ( t , ε ) approximates in asymptotic sense the infinite-dimensional set of solutions...

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