非自治动力系统Bowen估计熵的变分原理

推广了经典动力系统的Bowen拓扑熵,给出了非自治动力系统的Bowen估计熵的定义,讨论了非自治动力系统的Bowen估计熵和局部估计熵的关系,推广了自治动力系统Bowen拓扑熵的Billingsley型定理,研究了非自治动力系统的Bowen α-估计熵的Billingsley型定理.此外,给出了非自治动力系统Bowen...     

E.Ghys猜想的注记

通过类比自治动力系统中拓扑熵指数收敛的定义,给出了非自治拓扑熵指数收敛的定义及非自治Lipschitz系统中E.Ghys猜想成立的充分条件与必要条件,推广了自治动力系统中的相关结论.     

具非自治微小扰动的脉冲方程三个古典解的存在性

在半直线无穷区间上,我们研究具有微小非自治扰动项的脉冲方程边值问题的古典解,应用变分方法和相应的临界点理论得到了三个古典解的存在性.     

连续非自治系统的有限时间稳定性及其充分条件

本文研究了连续非自治系统的有限时间稳定性问题. 从一维连续非自治系统的有限时间稳定性分析入手, 本文通过使用比较原理, 获得了一些判定一般n维连续非自治系统的有限时间稳定性的充分条件,这些条件改善了已有的连续非自治系统有限时间稳定性的判定条件.     

三阶非线性非自治中立型时滞差分方程正解存在性定理

研究了一类三阶非线性变系数非自治中立型变时滞差分方程正解的存在性,给出了该类方程存在最终正解的几个充分条件,推广了已有文献的某些结果.     

非线性非自治系统零解的稳定性及部分稳定性研究

讨论了非线性非自治系统未被扰动运动的全变元及关于部分变元的稳定性、一致稳定性及全局稳定性，给出了几个判定准则，这些定理允许Lyapunov函数的导数为变号函数，改进了已有文献中的有关结果。     

非自治变时滞Cohen-Grossberg网络的Lagrange稳定性和全局指数吸引集

基于考虑两种不同类型的激活函数,本文研究了非自治变时滞Cohen-Grossberg神经网络（CGNN）在Lagrange意义下的全局指数稳定性,通过利用新的不等式技巧和构造恰当的Lyapunov泛函给出非自治变时滞CGNN模型在Lagrange意义下全局指数稳定性（即一致有界性）以及对其全局指数吸引集估计的代数判据,并给出应用例子加以验证.     

基于广义反射函数与自治系统等价的非自治系统

自治系统的研究比非自治系统要容易得多,以广义反射函数为前提,给出了等价于自治系统的非自治系统,从而将非自治系统的研究转化为自治系统的研究,并研究了该类系统的周期解及稳定性.     

非自治多种群时滞Kolmogorov系统的持续性和灭绝性

研究非自治多种群时滞Kolmogorov系统,给出了该系统中种群持续和灭绝的充分条件,并把得到的结果应用于非自治时滞Lotka-Volterra系统.把相关文献的有关结果推广到时滞系统.     

非强制位势下二阶非自治系统周期解的存在性

对于非自治二阶系统的位势函数在非强制情形下,利用归约方法和极大极小原理,充分借助空间分解的特性,利用子空间的特征,得到了关于该问题在梯度函数次线性或线性增长情形下新的存在性结果.     

Study of the blow-up of solutions of systems of equations of hydrodynamic type

Mathematical Notes - We study the initial boundary-value problem for three-dimensional systems of equations of pseudoparabolic type. The system is similar to the Oskolkov system, but differs from...     

Characterization of types of asymptotic discernibility of families of hypotheses

We give a characterization of the types of asymptotic discernibility of families of hypotheses in the case of hypothetical measures that are not, in general, mutually absolutely continuous. The case when the logarithm of the likelihood ratio admits an asymptotic expansion of the type of an expansion with local asymptotic normality is examined in detail. Examples are studied.Translated fromTeoriya Sluchainykh Protsessov, Vol. 15, pp. 64–71, 1987.     

Distribution of types of symmetry of tensors of high degree

The asymptotic distribution of tensors of degree N in symmetry types is studied in this paper.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 155, pp. 181–186, 1986.     

Axiomatizability of reducts of algebras of relations

In this paper, we prove that any subreduct of the class of representable relation algebras whose similarity type includes intersection, relation composition and converse is a non-finitely axiomatizable quasivariety and that its equational theory is not finitely based. We show the same result for subreducts of the class of representable cylindric algebras of dimension at least three whose similarity types include intersection and cylindrifications. A similar result is proved for subreducts of the class of representable sequential algebras. Received October 7, 1998; accepted in final form September 10, 1999.     

Lengths of periods of continued fractions of square roots of integers

Empirical study of the period’s length T of the continued fractions of $\sqrt{Q}$ (for growing integers Q) shows several strange asymptotical results, for instance, $T\leq C\sqrt{Q}\ln{Q}$ . These results show important differences between the statistics of the elements of the continued fractions of random real numbers and of square roots of random integers.