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Existence criteria for positive solutions of a nonlinear difference inequality

Sui ChengGuang Zhang — 2000

Annales Polonici Mathematici

This paper is concerned with a class of nonlinear difference inequalities which include many different classes of difference inequalities and equations as special cases. By means of a Riccati type transformation, necessary and sufficient conditions for the existence of eventually positive solutions and positive nonincreasing solutions are obtained. Various type of comparison theorems are also derived as applications, which extends many theorems in the literature.

Frequent oscillation in a nonlinear partial difference equation

Jun YangYu ZhangSui Cheng — 2007

Open Mathematics

This paper is concerned with a class of nonlinear delay partial difference equations with variable coefficients, which may change sign. By making use of frequency measures, some new oscillatory criteria are established. This is the first time oscillation of these partial difference equations is discussed by employing frequency measures.

Linearized comparison criteria for a nonlinear neutral differential equation

Xinping GuanSui Sun Cheng — 1996

Annales Polonici Mathematici

A class of nonlinear neutral differential equations with variable coefficients and delays is considered. Conditions for the existence of eventually positive solutions are obtained which extend some of the criteria existing in the literature. In particular, a linearized comparison theorem is obtained which establishes a connection between our nonlinear equations and a class of linear neutral equations with constant coefficients.

Mean stability of a stochastic difference equation

Viorica Mariela UngureanuSui Sun Cheng — 2008

Annales Polonici Mathematici

A simple personal saving model with interest rate based on random fluctuation of national growth rate is considered. We establish connections between the mean stochastic stability of our model and the deterministic stability of related partial difference equations. Then the asymptotic behavior of our stochastic model is studied. Although the model is simple, the techniques for obtaining its properties are not, and we make use of the theory of abstract Banach algebras and weighted spaces. It is hoped...

Kamenev type oscillation criteria for second order matrix differential systems with damping

Qi-gui YangSui Sun Cheng — 2005

Annales Polonici Mathematici

By using monotone functionals and positive linear functionals on a suitable matrix space, new oscillation criteria for second order self-adjoint matrix differential systems with damping are given. The results are extensions of the Kamenev type oscillation criteria obtained by Wong for second order self-adjoint matrix differential systems with damping. These extensions also include an earlier result of Erbe et al.

Eventually positive solutions for nonlinear impulsive differential equations with delays

Shao Yuan HuangSui Sun Cheng — 2012

Annales Polonici Mathematici

Several recent oscillation criteria are obtained for nonlinear delay impulsive differential equations by relating them to linear delay impulsive differential equations or inequalities, and then comparison and oscillation criteria for the latter are applied. However, not all nonlinear delay impulsive differential equations can be directly related to linear delay impulsive differential equations or inequalities. Moreover, standard oscillation criteria for linear equations cannot be applied directly...

Oscillation theorems for certain even order neutral differential equations

Qi Gui YangSui-Sun Cheng — 2007

Archivum Mathematicum

This paper is concerned with a class of even order nonlinear differential equations of the form d d t | x ( t ) + p ( t ) x ( τ ( t ) ) ( n - 1 ) | α - 1 ( x ( t ) + p ( t ) x ( τ ( t ) ) ) ( n - 1 ) + F ( t , x ( g ( t ) ) ) = 0 , where n is even and t t 0 . By using the generalized Riccati transformation and the averaging technique, new oscillation criteria are obtained which are either extensions of or complementary to a number of existing results. Our results are more general and sharper than some previous results even for second order equations.

Positive fixed point theorems arising from seeking steady states of neural networks

Gen Qiang WangSui-Sun Cheng — 2010

Mathematica Bohemica

Biological systems are able to switch their neural systems into inhibitory states and it is therefore important to build mathematical models that can explain such phenomena. If we interpret such inhibitory modes as `positive' or `negative' steady states of neural networks, then we will need to find the corresponding fixed points. This paper shows positive fixed point theorems for a particular class of cellular neural networks whose neuron units are placed at the vertices of a regular polygon. The...

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