非线性混合阶微分方程组的正解

主要研究了由不同阶微分方程构成的非线性微分方程组的正解的存在性问题,通过对非线性项进行限制,运用锥理论中的不动点定理,得到了方程组正解存在性的多个结果.     

带正同态算子的脉冲分数阶微分方程积分边值问题正解的多重性

本文关注带正同态算子的脉冲分数阶微分方程积分边值问题正解的多重性问题.利用经典的Guo-Krasnosel’skii不动点定理,给出了脉冲分数阶微分方程至少存在两个正解的充分条件.最后,用实例验证了理论结果的有效性.     

二阶共振多点边值问题正解的存在性

在不同共振条件下研究一类二阶非线性微分方程多点边值问题正解的存在性.利用范数形式的Leggett-Williams不动点定理,给出了问题正解的存在性结果,所得结论不同于已有文献.     

二阶常微分方程Neumann边值问题正解的全局分歧

本文考虑二阶常微分方程Neumann边值问题正解的存在性,其中f:[0,1]×R→R(R=(-∞,+∞))为连续函数.运用Dancer全局分歧定理建立了上述问题正解的全局分歧,并且获得了保证上述问题存在正解的若干最优充分条件.     

二阶三点边值问题正解的存在性

利用不动点指数定理研究了一类二阶非线性常微分方程的三点边值问题正解的存在性问题,得到了至少存在一个或无穷多个正解的几个充分条件.     

含一阶导数的二阶微分方程组多点边值问题正解的存在性

讨论了一类含一阶导数的二阶常微分方程组多点边值问题正解的存在性.利用一个新的不动点定理,得到上述问题具有一个正解的充分条件.     

含一阶导数的二阶微分方程组m点边值问题正解的存在性

讨论了二阶带一阶导数的微分方程组m点边值问题正解的存在性,利用一个新的不动点定理,得到上述问题具有一个正解的充分条件.     

四阶泛函微分方程边值问题正解的存在性

利用锥拉伸与锥压缩不动点定理,研究了一类四阶泛函微分方程边值问题正解的存在性,得到其正解及多个正解存在的若干充分条件,所得结果是相应常微分方程边值问题已有结论的拓广.     

具变号非线性项三阶多点边值问题的正解与多个正解

本文研究了一类非线性项变号的三阶常微分方程多点边值问题正解存在性问题.利用Banach空间锥上不动点定理及非线性泛函分析方法,获得了该问题正解的存在性结论.推广了已有文献的结果.     

一维p-Laplace二阶脉冲微分方程的奇异边值问题

脉冲现象作为一种瞬时突变现象,在现代科技各领域的实际问题中是普遍存在的.本文研究具有奇异边值的一维p-Laplace二阶微分方程在脉冲影响下的正解的存在性,介绍了解的一般性存在定理,并用A-A定理和不动点定理证明了一维p-Laplace二阶脉冲微分方程的奇异边值问题的正解存在性定理.     

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...     

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.     

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.     

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.