从“有限”到“无限”的跨越

数学教学过程中，如果将在有限范围内的思维定式或得到的结论推广到无限领域中去考虑问题或得出相应的结论，往往会导致结论的错误．在学习函数极限部分时，往往会出现求“∞∞，∞－∞，１∞”这三类来定型的极限．因学生在初中的思维定式是：ａａ＝１，ａ－ａ＝０，１ａ...     

“保护”

“金融危机宝宝”扎堆职场，应对可能到来的裁员风暴，保住现有的饭碗。     

实现从“变量说”到“对应说”的跨越——从整体上把握高中函数概念教学

1函数概念的三种定义函数一词是由莱布尼兹1673年最早引入的,用来表示任何一个随着曲线上的点变动而变动的量.例如,曲线上点的坐标、点的斜率、曲率半径等等.其后,伯努利把函数看作一个变量和一个常数组成的表达式.欧拉在伯努利之后把函数看作是含有变量和常数的任何方程和公式.不难看出,他们对函数的界定都没有跳出表达式的范围.     

BPR“强身操”

金融危机为急需“强身”的企业实施业务流程重组提供了练兵契机。己然明确BPR实施误区的企业,此刻尽可投身优美的BPR舞步实践中。     

拯救“钱荒”

又见钱荒。继2008年金融危机后,中国企业钱荒再现。央视的调查显示,在温州,大概有三成左右的企业出现资金困难,而且他们表示现在的情况比2008年还要更加严峻。     

“慎入”新兴市场基础设施

今天的新兴市场经济体要想重演当年罗斯福新政和中国抵御东亚金融危机的成功,将面临重重困难。     

这个“冬天”有多长

两年？还是三年？危机看似顷刻之间就发生了，但影响绝不可能在顷刻之间就消弭。要熬过这个冬天，仅有耐心是不够的。     

从“患寡”到“患不均”——共享视域下的相对贫困测度研究

在相对收入假说的基础上,借鉴福利主义解释什么是相对贫困,并在捋顺绝对贫困、强相对贫困、弱相对贫困的理论研究基础上,设计多参数收入分布拟合方法和相对贫困线校准方法,并利用CFPS (2010-2018)数据进行实证研究。研究发现:近年来我国绝对贫困水平下降明显,居民收入显著提高,但居民收入差距仍在高位徘徊;无论是下降幅度还是下降速度,与绝对贫困比较,相对贫困的变化都较为平缓;相对贫困是发展的贫困,在治理过程中应重视发展不平衡不充分的问题,提高低收入群体共享发展成果的能力。     

美国航企没被“套”

2007—2008年包括原油在内的大宗交易品价格发生大幅波动,导致中国涉外业务公司的业绩大幅下滑,部分对以原油为标的物实施套期保值策略的公司损失尤为惨重。根据公开披露信息,目前参与套保的28家央企中亏损的占多数：最近披露的公司年报,更是把原来企业认定的浮亏变成了巨额实亏：部分企业被ST,持续经营遭到严重挑战。表1是近期被媒体曝光的中国国内套保失败航空公司的有关数据。     

从“李约瑟难题”到“陈省身猜想”——学习钱学森教授关于数学科学的论述

美国数学家穆尔(E.H.Moore1862—1932)说过:“所有科学,包括逻辑和数学在内,都是时代的函数。”“李约瑟难题“和“陈省身猜想”,就其实质而言,两者都是“时代的函数”。本文以     

Dimension may exceed width

A partially ordered set with no infinite antichains may have arbitrarily large dimension.     

Continuously extending partial functions

We characterize those Hausdorff spaces in which continuous functions defined on compact subsets can be continuously extended to continuous functions defined on the space.

     

Continuously controlledA-theory

To anycontrolled space over the metric spaceB we can associate itsboundedly controlled algebraic K-theory, a functor designed to give information about the space of stable bounded concordances of manifolds homotopy equivalent toX. Generalizing a construction of D. R. Anderson, F. X. Connolly, S. Ferry, and E. K. Pedersen, we define another functor, calledcontinuously controlled A-theory, which depends only on thetopology of the control space, not itsmetric properties. In the special case whereB=R ₊, this functor is (more or less by definition) the same asproper A-theory. We prove that under certain conditions on the controlled space the natural transformation from boundedly controlledA-theory to continuously controlledA-theory is a weak homotopy equivalence, and hence defines a generalized homology theory. Continuously controlledK-theory is used in the approaches of G. Carlsson, E. K. Pedersen, and S. Ferry, S. Weinbergervto theK-theory Novikov conjecture.     

Some graphs whose second largest eigenvalue does not exceed 2

We determine all trees whose second largest eigenvalue does not exceed $\sqrt{2}$. Next, we consider two classes of bipartite graphs, regular and semiregular, with small number of distinct eigenvalues. For all graphs considered we determine those whose second largest eigenvalue is equal to $\sqrt{2}$. Some additional results are also given.     

On tricyclic graphs whose second largest eigenvalue does not exceed 1

A tricyclic graph of order n is a connected graph with n vertices and n + 2 edges. In this paper, all tricyclic graphs whose second largest eigenvalue does not exceed 1 are identified.     

On oriented graphs whose skew spectral radii do not exceed 2

Let S(G^σ)$S(G^{\sigma })$ be the skew adjacency matrix of the oriented graph G^σ$G^{\sigma }$ of order n   and _λ1,_λ2,…,_λn${\lambda }_1,{\lambda }_2,\dots ,{\lambda }_n$ be all eigenvalues of S(G^σ)$S(G^{\sigma })$. The skew spectral radius _ρs(G^σ)${\rho }_s(G^{\sigma })$ of G^σ$G^{\sigma }$ is defined as max{|_λ1|,|_λ2|,…,|_λn|}$\max \{|{\lambda }_1|,|{\lambda }_2|,\dots ,|{\lambda }_n|\}$. In this paper, we investigate oriented graphs whose skew spectral radii do not exceed 2.     

Subdivision of a Continuously Distributed Mass

Several theorems on subdivision of a mass continuously distributed on the plane, projective plane, or in space is proved by topological means. Bibliography: 7 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 299, 2003, pp. 228–240.