Block Covers and Module Covers of Finite Groups

Let G be a finite group, R a complete local principal ideal domain and peJ-(R). with p being a fixed prime, H≤G, B and B be an RG-block with idempot-ent e aud an RH-block with idempotent e respectively. The restriction of B as a     

包含圈的一些Ramsey数

用两种颜色,比如红和蓝,给完全图K_n的边着色.把着红色和蓝色的边集分别记为E_1和E_2,把K_n的边集分别是E_1和E_2的生成子图分别记为R和B,那么称R和B是K_n的一个分解,记为K_n=R⊕B.图G_1和G_2的Ramsey数,记为r(G_1,G_2),是使得K_n的任意一个分解K_n=R⊕B有R(?)G_1或B(?)G_2的最小正整数n.这里符号G(?)H表示图G包含子图H.此外,用C_n表示长为n的圈,GVH表示图G和H的联图.K_n表示n个相互独立的点,B_n指联图K_2     

GL_2 OVER FULL RINGS

In this paper the authors generalize the result of B.R.McDonald.The following resultis obtained.Let R be a(1,6)-full ring,or(3,3)-full ring,or(2,4)-full ring,and R has theproperty T.G is an SL_2(R)-normal subgroup of GL_2(R).Then there is an ideal A in Rsuch thatSC(R,A)(?)G(?)GC(R,A).     

也谈一个定值命题的推广

文 [1]证明了下面的命题 :命题 1　设P1、P2 、P3分别是正△ABC三边AB、BC、CA上的点 ,且AP1=BP2 =CP3,直线l为过正△ABC外接圆上任一点P的切线 ,则P1、P2 、P3三点到直线l的距离之和为定值 .文 [2 ]用解析法给出上面命题一个简洁证明 ,并将其“推广”为 :命题 2　设P1、P2 、P3分别是△ABC的三边AB、BC、CA上的点 ,且AP1∶P1B =BP2 ∶P2 C =CP3∶P3A =λ ,以△ABC的重心G为圆心 ,定长R为半径作⊙ (G ,R) ,直线l是⊙ (G ,R)的任意一条切线 ,则P1、P2 、P3三点到直线l的距离之和为定值 (3R) .笔者认为 ,命题 2是假…     

与群PSL2(R)相关的交叉积R(A,α)的一点注记

在上半复平面H上给定双曲测度dxdy/y2,群G=PSL2(R)在H上的分式线性作用导出了G在Hilbert空间L2(H,dxdy/y2)上的酉表示α.证明了交叉积R(A,α)是Ⅰ型von Neumann代数,其中A={Mf:f∈L∞(H,dxdy/y2)}.具体地,交叉积代数R(A,α)与von Neumann代数B(L2(P,v))-(×)LK是*-同构的,其中LK是G中子群K的左正则表示生成的群von Neumann代数.     

对一道高考试题的探究

依次类推 ,因此质点行走的折线段P0 P1P2 P3 P4便转化为直线段 P0 P1R1R2 R3 .容易证明 ,AB∥ A2 B2 ,AB=A2 B2 ,所以 ABB2 A2 是平行四边形 ,若 P0 P1延长后与平行四边形ABB2 A2 内的线段 CD1,D1A2 相交 ,并与 A2 B2相交 ,则线段 P0 R3 应在平行四边形 ABB2 A2的内部 ,因此必有∠ P0 B2 M <∠ P0 R3 M =∠ BP0 P1=θ <∠ P0 A2 M(这里 PM⊥B2 A2 的延长线于 M) .因为 AB=2 ,BC=1 ,所以 tan∠ P0 B2 M=MP0B2 M=25,tan∠P0 A2 M=MP0A2 M=23,又点 P4( R3 )位于点 P0 ( R0 )与点 B( B2 )之间 ,所以∠ P0 B2 …     

局部环上正交群中一类子群的扩群

定出了局部环上正交群中一类子群的扩群,得到了如下结果:设R是局部环,M是R的唯一极大理想,O(2m,R)为R上正交群.对R的任意理想S,G(2m,S)表示子群{A BC D∈O(2m,R)|B∈Sm×m}.如果char(R)≠2,m≥3,G(2m,0)≤X≤G(2m,M),那么存在R的理想S,使得X=G(2m,S).     

环与算子代数上中心化子的刻画

令R是含有单位元I和一非平凡幂等元P的环.假设Φ:R→R是可加映射,A,B∈R.本文证明了,在一些徽弱的假设下,下列表述成立:(1)Φ满足AB=P蕴涵Φ(A)B=AΦ(B)=Φ(P)当且仅当Φ是中心化子;(2)Φ满足AB+BA=P蕴涵Φ(A)B+Φ(B)A=Φ(P)(AΦ(B)+BΦ(A)=Φ(P))当且仅当圣是左(右)中心化子;(3)Φ满足AB+BA=0蕴涵Φ(A)B+Φ(B)A=0(AΦ(B)+BΦ(A)=0)当且仅当Φ是左(右)中心化子.作为应用,获得了三角代数、套代数、因子von Neumann代数等算子代数上中心化子的刻画.     

BACKWARD STOCHASTIC DIFFERENTIAL EQUATION WITH RANDOM MEASURES

1. IntroductionPardoux and Peng[1], Peng[2'3] have discussed backward stochastic differential equations(BSDE) driven by Brownian motioll. Tangl4], Tang and Li[5] have considered BSDEdriven by Brownian motion and Poisson process. We will extend many results of them inthis paper.The main reference is [6].Let (fi, F, (R),P) be a filtered probability space, where the filtration (R) satisfies theusual conditions. Define (fi,F) ~ (fi x N x R,X x B(N) x B(R)),P ~ P x B(R), O =O x B(R),…     

Special α-limit points and unilateral γ-limit points for graph maps

Let G be a graph and f:G → G be a continuous map.Denote by P(f),R(f),SA(f) and U Γ(f) the sets of periodic points,recurrent points,special α-limit points and unilateral γ-limit points of f,respectively.In this paper,we show that R(f)SA(f) = U Γ(f)∪P(f)■.     

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.     

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}.     

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].     

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 …     

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 NOTE ON A COVERING LEMMA OF A CORDOBA AND R FEFFERMAN~(**)

This note simplifies Cordoba-Fefferman's proof on the weak boundedness of strong maximal operator M_8 (with respect to dμ) on L(1+log~(+(n-1))L). Some two-weighted boundedness results on L(1+log~(+α)L) of M_8 are investigated.