Quasi-linear Quotients and Shellability of Pure Simplicial Complexes

For a square-free monomial ideal I ? S = k[x ₁, x ₂,…, x _n ], we introduce the notion of quasi-linear quotients. By using the quasi-linear quotients, we give a new algebraic criterion for the shellability of a pure simplicial complex Δ over [n]. Also, we provide a new criterion for the Cohen–Macaulayness of the face ring of a pure simplicial complex Δ. Moreover, we show that the face ring of the spanning simplicial complex (defined in [2 Anwar , I. , Raza , Z. , Kashif , A. Spanning simplicial complexes of uni-cyclic graphs . To appear in Algebra Colloquium . [Google Scholar]]) of an r-cyclic graph is Cohen–Macaulay.     

Collapses, products and LC manifolds

The quantum physicists Durhuus and Jonsson (1995) [9] introduced the class of “locally constructible” (LC) triangulated manifolds and showed that all the LC 2- and 3-manifolds are spheres. We show here that for each d>3 some LC d-manifolds are not spheres. We prove this result by studying how to collapse products of manifolds with one facet removed.     

随机变量的和、积、商分布的一种新表示

应用Feller提出的点-集函数并结合二元copula,对二元连续型正值随机变量的和、积、商的分布进行了研究,得到了和、积、商分布的一种新的计算方法.最后给出一个应用实例.     

Comparison of Certain Complexes of Modules of Generalized Fractions and Čech Complexes

We establish an explicit quasi-isomorphism of complexes, which is homogeneous in graded situation, from a given ?ech complex to a certain complex of modules of generalized fractions. This leads to characterizations of local cohomology and ideal transforms of a module. Also, in this note, we study the behavior of generalized fraction formation along exact sequences and vanishing of modules of generalized fractions in certain cases.     

A Compact Space Is Homotopy Equivalent to a CW-Complex If and Only If It Is an Absolute Neighborhood h-Retract

It is proved that a compact space is homotopy equivalent to a CW-complex if and only if it is an absolute neighborhood h-retract.     

Two acyclicizations of a complex and an explicit recollement

By assigning to each complex over a semi-simple ring two acyclicizations, we construct an explicit recollement for homotopy categories of a certain triangular matrix ring such that all the six triangle functors of the recollement preserve acyclic complexes.     

Studies on Jacobi–Davidson,Rayleigh quotient iteration,inverse iteration generalized Davidson and Newton updates

We study Davidson‐type subspace eigensolvers. Correction equations of Jacobi–Davidson and several other schemes are reviewed. New correction equations are derived. A general correction equation is constructed, existing correction equations may be considered as special cases of this general equation. The main theme of this study is to identify the essential common ingredient that leads to the efficiency of a diverse form of Davidson‐type methods. We emphasize the importance of the approximate Rayleigh‐quotient‐iteration direction. Copyright © 2006 John Wiley & Sons, Ltd.     

Stable Projective Homotopy Theory of Modules,Tails, and Koszul Duality

A contravariant functor is constructed from the stable projective homotopy theory of finitely generated graded modules over a finite-dimensional algebra to the derived category of its Yoneda algebra modulo finite complexes of modules of finite length. If the algebra is Koszul with a noetherian Yoneda algebra, then the constructed functor is a duality between triangulated categories. If the algebra is self-injective, then stable homotopy theory specializes trivially to stable module theory. In particular, for an exterior algebra the constructed duality specializes to (a contravariant analog of) the Bernstein–Gelfand–Gelfand correspondence.     

实对称型上的Schur子空间及应用

本文构作了Schur型多项式,将其作为研究实对称型的基础.研究了具有零点(1,1,...,1)的实对称型形成的子空间,即Schur子空间.建立了这种子空间的构造性理论,并应用于计算(构造)实代数几何中比较关心的对称型正性判定问题,以及给出一些特殊类型的Hilbert第17问题的构造解.     

Configurations, braids, and homotopy groups

The main results of this article are certain connections between braid groups and the homotopy groups of the -sphere. The connections are given in terms of Brunnian braids over the disk and over the -sphere. The techniques arise from the natural structure of simplicial and -structures on fundamental groups of configuration spaces.

     

Alexandroff's Double Arrow Compact Space and Approximation Theory

A compact space Q similar to the compact space known as Alexandroff's double arrow space is constructed. It is shown that the real space C(Q) has no Chebyshev subspaces of codimension >1, but the complex space C(Q) has such subspaces.     

Compact open topology and CW homotopy type

The class of spaces having the homotopy type of a CW complex is not closed under formation of function spaces. In 1959, Milnor proved the fundamental theorem that, given a space and a compact Hausdorff space X, the space Y^X of continuous functions X→Y, endowed with the compact open topology, belongs to . P.J. Kahn extended this in 1982, showing that if X has finite n-skeleton and π_k(Y)=0, k>n.

Using a different approach, we obtain a further generalization and give interesting examples of function spaces where is not homotopy equivalent to a finite complex, and has infinitely many nontrivial homotopy groups. We also obtain information about some topological properties that are intimately related to CW homotopy type.

As an application we solve a related problem concerning towers of fibrations between spaces of CW homotopy type.     

有限区间小波子空间上的采样定理及H~2(I)空间中函数的逼近表示

给出有限区间 [0 ,L ]小波子空间上的 Shannon型采样定理 .它是应用再生核空间理论和Riesz基的对偶性质得到的 .另外 ,根据得到的采样定理 ,讨论了 Sobolev空间 H20 ( I)和 H2 ( I)中的函数、一阶导函数及二阶导函数的逼近表示 .最后给出相应的数值算例     

Isolated complex singularities and their CR links

In this paper, we discuss some recent studies on the complex structure of an isolated normal singularity by using the information from its link. We also give some open problems to be further pursued. Dedicated to Professor Sheng GONG on the occasion of his 75th birthday     

Isolated complex singularities and their CR links Dedicated to Professor Sheng GONG on the occasion of his 75th birthday

In this paper, we discuss some recent studies on the complex structure of an isolated normal singularity by using the information from its link. We also give some open problems to be further pursued.