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1.
About 1923,the great mathematician Paul Lévy invented a family of probabilitydistributions(laws)called"stable".If X and Y are independent random variableswith the law L,then for any constants a>0 and b,there exist constants c>0 andd such that the law of aX+bY is the same as cZ+d,where Z is a random variable  相似文献   

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A well-known Ingelstam's Theorem asserts that every real Hilbert space A with an associative unital product satisfying ‖ xy‖ ≤ ‖ x‖ ‖ y‖ and ‖ 1‖ = 1 is isomorphic to the reals ?, or the complex numbers ?, or the quaternions ?. This note deals with a nonunital and nonassociative extension of the Ingelstam Theorem. So the assumptions about associativity and existence of unity are weakened to the existence of a nonzero central idempotent e such that ‖ ex‖ = ‖e‖ ‖ x‖ for all x, and that in A holds a determined kind of algebraic identity strictly weaker that alternativeness. We prove that, up to isomorphisms, there are only seven algebras satisfying these assumptions, even without the requirement of completeness. On the other hand, Section 3 presents another characterization of the obtained algebras with the flavor of one of the main theorems in Bhatt et al. (1998 Bhatt , S. J. , Karia , D. J. , Kulkarni , S. H. , Shimpi , M. E. ( 1998 ). A note on the Gelfand-Mazur theorem . Proc. Amer. Math. Soc. 126 ( 10 ): 29993005 .[Crossref], [Web of Science ®] [Google Scholar]).  相似文献   

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We prove a theorem giving conditions under which a discrete-time dynamical system as (x t ,y t ) = (f;(x t – 1, y t – 1), g(x t – 1, y t – 1)) can be reconstructed from a scalar valued time series ( t ) t , which depends only on x t where t = (x t ). This theorem allows us to use the delay-coordinate method in this setting.  相似文献   

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本文在无线性结构H-空间的框架之下给出一个新的von Neumann型非紧极大极小定理,并且作为其应用而得到一个新的Ky Fan型截口定理和一个新的非空交定理.结果即使在欧几里得空间中也是全新的  相似文献   

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Skew lattices form a class of non-commutative lattices. Spinks' Theorem [Matthew Spinks, On middle distributivity for skew lattices, ] states that for symmetric skew lattices the two distributive identities and are equivalent. Up to now only computer proofs of this theorem have been known. In the present paper the author presents a direct proof of Spinks' Theorem. In addition, a new result is proved showing that the assumption of symmetry can be omitted for cancellative skew lattices.  相似文献   

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We consider Carathéodory functions f : T × X Y, where T is a topological space with regular -finite measure, the spaces X and Y are metrizable and separable, and X is locally compact. We show that every function of this sort possesses the Scorza-Dragoni property. A similar result is also established in the case where the space T is locally compact and X = .  相似文献   

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We give a new proof of Bartholdi's theorem for the Bartholdi zeta function of a graph. Supported by Grant-in-Aid for Science Research (C)  相似文献   

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FU Xiao-yong 《数学季刊》2007,22(4):550-551
We give a new proof of Calabi-Yau's theorem on the volume growth of Riemannian manifolds with non-negative Ricci curvature.  相似文献   

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一个由n个非负整数有序对构造的序列是有向可图的,如果它是某个有向图的度序列.一个有向可图序列是蕴含强连通的,如果它是某个强连通有向图的度序列.Beineke和Harary给出了一个有向可图序列为蕴含强连通的判准.Beineke-Harary判准的充分性证明是“相当长”的(见[1]).本文的目的是给出Beineke-Harary判准的充分性的一个简短证明.  相似文献   

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利用随机不动点指数,研究了随机半闭1-集压缩算子方程的随机解,同时,从不同角度推广了著名的Krasnoselskii定理,得出若干新的结果.  相似文献   

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We give a new proof of Calabi-Yau's theorem on the volume growth of Rie- mannian manifolds with non-negative Ricci curvature.  相似文献   

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一个新的极大极小定理及应用   总被引:1,自引:0,他引:1  
本文得到一个新的极大极小定理及其几个等价形式.作为这一结果的应用,我们得到区间空间上的Ky Fan型截口定理,匹配定理和几个集值映象的不动点定理.  相似文献   

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柯西积分定理的一个新证明   总被引:1,自引:0,他引:1  
我们利用调和分析的方法给出了柯西积分定理的一个新的证明,我们的证明比古莎所给出的证明简单.  相似文献   

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We present some applications of the Subspace Theorem to the investigation of the arithmetic of the values of Laurent series f(z) at S-unit points. For instance we prove that if f(q n ) is an algebraic integer for infinitely many n, then h(f(q n )) must grow faster than n. By similar principles, we also prove diophantine results about power sums and transcendency results for lacunary series; these include as very special cases classical theorems of Mahler. Our arguments often appear to be independent of previous techniques in the context.  相似文献   

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As an extension of earlier papers on stationary sequences, a concept of weak dependence for strictly stationary random fields is introduced in terms of so-called homoclinic transformations. Under assumptions made within the framework of this concept a form of the almost sure central limit theorem (ASCLT) is established for random fields arising from a class of algebraic Z d -actions on compact abelian groups. As an auxillary result, the central limit theorem is proved via Ch. Stein's method. The next stage of the proof includes some estimates which are specific for ASCLT. Both steps are based on making use of homoclinic transformations.  相似文献   

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