Browder定理和Weyl定理

本文通过定义两个新的谱集,给出了Browder定理和Weyl定理对算子T以及f(T)成立的充要条件,其中f∈H(σ(T)),H(σ(T))表示在谱集σ(T)的开邻域上解析的函数的全体。     

用区间套定理证明Darboux定理

Darboux定理是数学分析中的一个重要定理.在已有文献的基础上,对该定理作了进一步的研究,利用区间套定理给出了它的新的证明方法.证明思路与现有的其它证明思路是不同的.     

Brooks’ Theorem via the Alon-Tarsi Theorem

We give a proof of Brooks’ Theorem and its choosability extension based on the Alon-Tarsi Theorem; this also shows that Brooks’ Theorem remains valid in a more general game coloring setting.     

Cauchy-Binet定理与Laplace定理的等价证明

本文运用分块矩阵及多元多项式的性质对行列式求值中的Cauchy-Binet 定理与Laplace 定理给出了等价证明.     

H-空间中新的非紧极大极小定理、截口定理及非空交定理

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     

Menger's Theorem

Menger's Theorem for digraphs states that for any two vertex sets A and B of a digraph D such that A cannot be separated from B by a set of at most t vertices, there are t + 1 disjoint A–B‐paths in D. Here a short and elementary proof of a more general theorem is given. © 2001 John Wiley & Sons, Inc. J Graph Theory 37: 35–36, 2001     

没有线性结构的极大极小定理与鞍点定理

在没有线性结构的一般集合上引入了函数的一种“凹（凸）”性概念，得到一个没有线性结构的ＦａｎＫｙ不等式；在此基础上，在一般的拓扑空间上建立了极大极小定理，并把著名的鞍点定理推广到没有线性结构的拓扑空间上·     

广义Cauchy中值定理及其逆定理

将C auchy中值定理的条件进行适当减弱,得到了广义C auchy中值定理,从而推广了C auchy中值定理,并在凸函数的条件下,证明了其逆定理亦成立.     

Theorem A und Theorem B in der nichtarchimedischen Funktionentheorie

Ohne Zusammenfassung     

On the Equivalence and Generalized of Weyl Theorem Weyl Theorem

We know that an operator T acting on a Banach space satisfying generalized Weyl＇s theorem also satisfies Weyl＇s theorem. Conversely we show that if all isolated eigenvalues of T are poles of its resolvent and if T satisfies Weyl＇s theorem, then it also satisfies generalized Weyl＇s theorem. We give also a sinlilar result for the equivalence of a-Weyl＇s theorem and generalized a-Weyl＇s theorem. Using these results, we study the case of polaroid operators, and in particular paranormal operators.     

General Embedding Theorem

The quotient space of an arbitrary Banach space B by any subspace B₁ ? B equipped with the norm \(||b|B/{B_1}|| = \mathop {\inf }\limits_{f \in B/{B_1}} ||f|b||\) is considered. In the case where the infimum is a minimum, i.e., it is attained at some element, a formula for this element is presented. The proof is based on restating the original problem in dual spaces with the help of corresponding Legendre transforms. Although the original problem is nonlinear, it is found that its formulation in dual spaces is always linear and solvable. The results are applied to the general theory of boundary value problems for differential equations of mathematical physics.     

On McEliece's Theorem

A new simple proof of the well-known theorem of McEliece about the complete weight enumerators of ternary self-dual codes is given.     

Lipschitz Flow-box Theorem

A generalization of the Flow-box Theorem is proven. The assumption of a C¹ vector field f is relaxed to the condition that f be locally Lipschitz continuous. The theorem holds in any Banach space.     

Kolmogorov Theorem revisited

Kolmogorov Theorem on the persistence of invariant tori of real analytic Hamiltonian systems is revisited. In this paper we are mainly concerned with the lower bound on the constant of the Diophantine condition required by the theorem. From the existing proofs in the literature, this lower bound turns to be of O(ε1/4), where ε is the size of the perturbation. In this paper, by means of careful estimates on Kolmogorov's method, we show that this lower bound can be weakened to be of O(ε1/2). This condition coincides with the optimal one of KAM Theorem. Moreover, we also obtain optimal estimates for the distance between the actions of the perturbed and unperturbed tori. We believe that some ideas contained in this paper may be used for improving several estimates in the general KAM context.     

The Sylvester-Chvatal Theorem

The Sylvester-Gallai theorem asserts that every finite set S of points in two-dimensional Euclidean space includes two points, a and b, such that either there is no other point in S on the line ab, or the line ab contains all the points in S. Chvatal extended the notion of lines to arbitrary metric spaces and made a conjecture that generalizes the Sylvester-Gallai theorem. In the present article we prove this conjecture.     

Annihilation Theorem and Separation Theorem for basic classical Lie superalgebras

In this article we prove that for a basic classical Lie superalgebra the annihilator of a strongly typical Verma module is a centrally generated ideal. For a basic classical Lie superalgebra of type I we prove that the localization of the enveloping algebra by a certain central element is free over its centre.

     

Weyl's Theorem, a-Weyl's Theorem, and Local Spectral Theory

Necessary and sufficient conditions are given for a Banach spaceoperator with the single-valued extension property to satisfyWeyl's theorem and a-Weyl's theorem. It is shown that if T orT^* has the single-valued extension property and T is transaloid,then Weyl's theorem holds for f(T)for every fH((T)). When T^*has the single-valued extension property, T is transaloid andT is a-isoloid, then a-Weyl's theorem holds for f(T) for everyfH((T)). It is also proved that if T or T^* has the single-valuedextension property, then the spectral mapping theorem holdsfor the Weyl spectrum and for the essential approximate pointspectrum.     

完备随机赋范模中的Drop定理与Petal定理

在随机赋范模中给出了L0-drop的定义并在局部L0-凸拓扑下证明了完备随机赋范模中的Drop定理与Petal定理,然后证明了它们与此拓扑下完备随机赋范模中的Ekeland变分原理是相互等价的;进而,利用(ε,λ)-拓扑与局部L0-凸拓扑下基本结果之间的联系,得到了(ε,λ)-拓扑下完备随机赋范模中的Drop定理与Petal定理以及它们与该拓扑下完备随机赋范模中的Ekeland变分原理之间的等价性.