具有以双曲线与赤道弧为边界的周期环域的二次系统的Poincare分支及…

本文讨论了一类具有以双曲线与赤道弧为边界的周期环域的二次系统的Ｐｏｉｎｃａｒｅ分支，分别举出了此系统在一个奇点外围恰好存在两个单重环；恰发存在一个二重环；恰好存在一个单重环和一个无穷大分界线环等例子。     

关于一类扰动系统的极限环上界问题

本文讨论了一类扰动系统在其一阶Ｍｅｌｎｉｋｏｖ函数恒为零,而二阶Ｍｅｌｎｉｋｏｖ函数不恒为零时的Ｐｏｉｎｃａｒｅ分支及Ｈｏｐｆ分支的有关问题,得到了该系统的极限环个数的上界估计,本文推广并深化了文「４」的结论,也弥补了该文的某些不足。     

完整动力系统的积分不变量

本文利用Ｐｏｉｎｃａｒｅ形式研究了一个保守完整动力系统的积分不变量，对异步变分引入了新的参数，给出了Ｐｏｉｎｃａｒｅ和Ｐｏｉｎｃａｒｅ－Ｃａｒｔａｎ积分不变量的一个推广。     

整体Poincare截面存在性的拓扑障碍

本文讨论了流形上流的整体Ｐｏｉｎｃａｒｅ截面的存在性,并证明了流形的一般拓扑导致整体Ｐｏｉｎｃａｒｅ截面的存在性的障碍。     

扰动双中心Hamiltonian系统的分支

本文对一类具双中心的二次Ｈａｍｉｌｔｏｎｉａｎ扰动系统的Ｈｏｐｆ分支、Ｐｏｉｎｃａｒé分支进行了研究，并讨论了能否在双中心同时产生极限环的问题     

渐近时间周期系统

本文证明了渐近时间周期系统的Ｐｏｉｎｃａｒｅ映射的极限集是极限系统的Ｐｏｉｎｃａｒｅ映射的不变集。     

同宿分支、广义Hopf分支和马蹄

本文考虑弱吸引条件下的Ｓｉｌ＇ｎｉｋｏｖ现象，证明了相应的Ｐｏｉｎｃａｒｅ映射具有马蹄构造，并且，伴随着广义Ｈｏｐｆ分支，将产生新的同宿轨道、异宿轨道以及更复杂的混沌现象．     

广义Lienard方程周期解不存在性

本文利用Ｐｏｉｎｃａｒｅ切性曲线法，对广义Ｌｉｅｎａｒｄ方程给出了其周期解不存在的两类充分条件，得到了比文［１］更广泛的结果．     

Poincare动力学方程Whittaker降阶法

Ｗｈｉｔｔａｋｅｒ降阶法是利用能量积分将一个完整动力系统的Ｌａｇｒａｎｇｅ运动方程降阶。本文论述了据李群理论构造的Ｐｏｉｎｃａｒｅ方程所描述的非完整保守系统的相应结果。     

食饵有常数放养率的广义Roseeenzweig—Macarthur系统

本文运用Ｌｉａｐｕｎｏｖ第二方法,研究了食饵有常数放养率的广义Ｒｏｓｅｎｚｗｅｉｇ－Ｍａｃａｒｔｈｕｒ系统｛ｘ＾&;#183;＝ｆ（ｘ）－ｙψ（ｘ）＋Ｈ,ｙ＾&;#183;＝ｈ（ｙ）「－ｅ＋Ｋψ（ｘ）」唯一正平衡点的稳定性。并利用Ｐｏｉｎｃａｒｅ－Ｂｅｎｄｉｘｏｎ环域定理及张芷芬唯一性定理,论证了在Ｒ＾＋２＝｛（ｘ,ｙ）：ｘ〉０,ｙ〉０｝内极限环的存在唯一性及其稳定性。     

A Priori and A Posteriori: A Bootstrapping Relationship

The distinction between a priori and a posteriori knowledge has been the subject of an enormous amount of discussion, but the literature is biased against recognizing the intimate relationship between these forms of knowledge. For instance, it seems to be almost impossible to find a sample of pure a priori or a posteriori knowledge. In this paper, it will be suggested that distinguishing between a priori and a posteriori is more problematic than is often suggested, and that a priori and a posteriori resources are in fact used in parallel. We will define this relationship between a priori and a posteriori knowledge as the bootstrapping relationship. As we will see, this relationship gives us reasons to seek for an altogether novel definition of a priori and a posteriori knowledge. Specifically, we will have to analyse the relationship between a priori knowledge and a priori reasoning, and it will be suggested that the latter serves as a more promising starting point for the analysis of aprioricity. We will also analyse a number of examples from the natural sciences and consider the role of a priori reasoning in these examples. The focus of this paper is the analysis of the concepts of a priori and a posteriori knowledge rather than the epistemic domain of a posteriori and a priori justification.     

ON A THEOREM OF A.A. LYAPUNOV

Abstract

In this note we obtain some extensions and an approximation of the Lyapunov convexity theorem by means of the bilinear integration of a set-valued function. The integration is performed successively with respect to a non-atomic, a direct sum and a Darboux vector measure. The necessary counterexamples are provided.     

有限群的一个类函数的模构造

本文研究了有限群上的一个类函数.通过计算它和不可约特征标的内积,证明了它是特征标并且通过复群代数的中心的正则表示给出了它的一个模构造.     

A new characterization of A 5

Let G be a group and τ _e (G) the set of numbers of elements of G of the same order. In this paper, by τ _e (G), we give a new characterization of A ₅, where A ₅ is the alternating group of degree 5. We get the theorem following: Theorem. Let G be a group, ${G\cong A_5}$ if and only if τ _e (G) = τ _e (A ₅) = {1, 15, 20, 24}.     

A REMARK ON A BMO MARTINGALE

Let M = (Mt,Ft) be a uniformly integrable continuous martingale with MO = 0. For1 5 p < cot we setIIMllBMO. = '3p II[E[IMoo ~ MTIplFT]]'/Pll.,where the supremum is taken over all stopping times T.Set BMO. = {M: IIMllBMO. < co}. It is well known that BMO. = BMO, (VI S p 5 q).F'urthermore, all 11.llBMO. norms are equivalent andIIi ~~if;llMllBMO. = SUP T P(T < co)i'where the supremum is taken over all stopping times T satisfying P(T < co) > 0. In the laterwe shall simply …     

NAMING A COLUMN ON A SPREADSHEET

Spreadsheets use a meaningful algebra-like notation which, research suggests, can support pupils in developing an understanding of variables. This paper discusses the activity of Year 8 pupils who were taught to name a column on a spreadsheet, and who were asked to reflect upon their activity in a stimulated recall interview. More specifically, it considers the pupils' understanding of notation, such as 'A2' and 'm', which they used when constructing spreadsheet formulae. It is suggested that experience of naming columns may help pupils to develop a clearer sense of the notation as a variable, and to make links between their spreadsheet activity and use of standard algebraic notation [1].