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91.
Noga Alon 《Journal of Number Theory》2007,126(1):110-118
For a prime p, a subset S of Zp is a sumset if S=A+A for some A⊂Zp. Let f(p) denote the maximum integer so that every subset S⊂Zp of size at least p−f(p) is a sumset. The question of determining or estimating f(p) was raised by Green. He showed that for all sufficiently large p, and proved, with Gowers, that f(p)<cp2/3log1/3p for some absolute constant c. Here we improve these estimates, showing that there are two absolute positive constants c1,c2 so that for all sufficiently large p,
92.
吴慧卓 《纯粹数学与应用数学》2003,19(1):16-21
典型的进化策略受自然进化过程的启发而成为求解全局优化问题的重要方法。传统的ES变异算子作为一个主要的进化技术是建立在正态分布的随机变量基础上的,本文提出了基于指数分布的进化策略由于采用了新的变异算子有效地减少了产生探试解的成本,从而优于传统的进化策略。 相似文献
93.
94.
T. S. K. Moothathu 《Annals of the Institute of Statistical Mathematics》1985,37(1):473-479
Summary This paper presents the maximum likelihood estimators (MLEs) of the Lorenz curve and Gini index of the exponential distribution,
their exact distributions and moments. All these MLEs are shown to converge almost surely and in therth mean. Further their asymptotic distributions are obtained. Here we use only very simple arguments to derive certain results
that are very useful in statistical study of ‘inequality’. 相似文献
95.
96.
Thomas Wanner 《Transactions of the American Mathematical Society》2004,356(6):2251-2279
Many interesting and complicated patterns in the applied sciences are formed through transient pattern formation processes. In this paper we concentrate on the phenomenon of spinodal decomposition in metal alloys as described by the Cahn-Hilliard equation. This model depends on a small parameter, and one is generally interested in establishing sharp lower bounds on the amplitudes of the patterns as the parameter approaches zero. Recent results on spinodal decomposition have produced such lower bounds. Unfortunately, for higher-dimensional base domains these bounds are orders of magnitude smaller than what one would expect from simulations and experiments. The bounds exhibit a dependence on the dimension of the domain, which from a theoretical point of view seemed unavoidable, but which could not be observed in practice.
In this paper we resolve this apparent paradox. By employing probabilistic methods, we can improve the lower bounds for certain domains and remove the dimension dependence. We thereby obtain optimal results which close the gap between analytical methods and numerical observations, and provide more insight into the nature of the decomposition process. We also indicate how our results can be adapted to other situations.
97.
连续型单参指数族参数的经验Bayes检验问题:NA样本情形 总被引:8,自引:0,他引:8
本文对连续型单参指数族单边和双边假设检验问题导出了Bayes检验函数 ,利用同分布NA样本构造了经验Bayes(EB)检验函数 ,在适当条件下证明了EB检验函数的渐近最优性并获得了其收敛速度 ,文末给出一个满足定理条件的例子 相似文献
98.
研究了一类不同分布两两NQD列的Jamison型加权乘积和的强稳定性,推广了不同分布独立列部分和与同分布NQD列部分和情形相类似的结论. 相似文献
99.
GLOBAL EXPONENTIAL STABILITY IN HOPFIELD AND BIDIRECTIONAL ASSOCIATIVE MEMORY NEURAL NETWORKS WITH TIME DELAYS 下载免费PDF全文
Without assuming the boundedness, strict monotonicity and differentiability of the activation functions, the authors utilize the Lyapunov functional method to analyze the global convergence of some delayed models. For the Hopfield neural network with time delays, a new sufficient condition ensuring the existence, uniqueness and global exponential stability of the equilibrium point is derived. This criterion concerning the signs of entries in the connection matrix imposes constraints on the feedback matrix independently of the delay parameters. From a new viewpoint, the bidirectional associative memory neural network with time delays is investigated and a new global exponential stability result is given. 相似文献
100.
Toka Diagana Gaston Nguerekata Nguyen Van Minh 《Proceedings of the American Mathematical Society》2004,132(11):3289-3298
This paper is concerned with the existence of almost automorphic mild solutions to equations of the form
where generates a holomorphic semigroup and is an almost automorphic function. Since almost automorphic functions may not be uniformly continuous, we introduce the notion of the uniform spectrum of a function. By modifying the method of sums of commuting operators used in previous works for the case of bounded uniformly continuous solutions, we obtain sufficient conditions for the existence of almost automorphic mild solutions to in terms of the imaginary spectrum of and the uniform spectrum of .
where generates a holomorphic semigroup and is an almost automorphic function. Since almost automorphic functions may not be uniformly continuous, we introduce the notion of the uniform spectrum of a function. By modifying the method of sums of commuting operators used in previous works for the case of bounded uniformly continuous solutions, we obtain sufficient conditions for the existence of almost automorphic mild solutions to in terms of the imaginary spectrum of and the uniform spectrum of .